Kite Aur Uski Properties | Class 8 Maths Book 1 Ch 4

📘 Class 8 · Ganita Prakash Book 1Ch 4 · QuadrilateralsPost 6 / 8⏱ 25–30 min
Kite Aur Uski Properties 🪁

✅ Pehle Yeh Aata Hai?

Yeh post shuru karne se pehle, in teen sawaalon ko 1 minute mein khud try kijiye:

  1. SSS aur SAS?
  2. Rhombus ke diagonals?
  3. Symmetry line kya hoti?
Answers dekho
  1. Congruence ki shartein
  2. 90° pe aur ek doosre ko aadha
  3. Jis pe modne se dono hisse milte

Teeno sahi? Badhiya, aage chaliye! Koi galat hua? Koi baat nahi, Post 5 — Rhombus Ki Properties dobara dekh lijiye.

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🎬 Kahani: Makar Sankranti Ki Patang

Sankranti pe chhat pe Golu patang bana raha tha. Do baans ke dande: ek lamba, ek chhota. Dadaji: “Chhota danda lambe ke thik upar ki taraf baandho, beech mein nahi. Aur dono 90° pe!” 🪁

Golu: “Beech mein kyun nahi?” Dadaji: “Beech mein baandhoge to rhombus banega, patang nahi! Aur 90° na hua to patang tedhi udegi.”

Dadaji ki yeh dono baatein maths se aati hain. Patang (kite) ke gun kya hain, aur kyun? Chaliye dekhte hain. 🧵

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📖 Concept: Do Jodi Padosi Sides Barabar

💡 Is post ki ek badi baat: Kite = quadrilateral jisme padosi sides ki do jodi barabar: AB = BC aur CD = DA. Isse beech wali diagonal (BD) ek mirror line ban jaati: woh kone B, D ko aadha karti aur doosri diagonal ko 90° pe aadha.

Step 1: Paribhaasha aur chitra

Kite ABCD: BA = BC = 7, DA = DC = 11; diagonal BD, diagonal AC ko O pe 90° pe aadha karti haiBCDAO90°771111
Kite ABCD: BA = BC = 7, DA = DC = 11; diagonal BD, diagonal AC ko O pe 90° pe aadha karti hai

B ke dono taraf 7-7, D ke dono taraf 11-11. Barabar sides padosi hain (saamne nahi): yahi parallelogram se farak.

Step 2: Gun 1: BD kone aadha karti

△ABD aur △CBD: BA = BC, DA = DC, BD common → SSS → ∠ABD = ∠CBD, ∠ADB = ∠CDB, aur ∠A = ∠C.

WHY? BD ke dono taraf bilkul ek jaise triangle: mirror image. Patang ko BD pe modo, dono aadhe milte!

Step 3: Gun 2: BD, AC ko 90° pe aadha karti

△ABO aur △CBO: BA = BC, ∠ABO = ∠CBO (gun 1), BO common → SAS → AO = CO aur ∠AOB = ∠COB.

Dono milke 180° → 90° har ek. To BD, AC ki perpendicular bisector hai.

Par ulta nahi! AC, BD ko aadha nahi karti (O, BD ke beech mein nahi). Dadaji ka “upar ki taraf baandho” yahi hai.

Step 4: Do triangle jod ke aakaar

Ek triangle (sides 10, 10, 7) aur uski copy lo:

  • Lambi sides (10) milao, ulta (mirror) → kite (10, 7, 7, 10)
  • Lambi side milao, ghuma ke → parallelogram (10, 7, 10, 7)
  • Chhoti side (7) milao, mirror → rhombus (10, 10, 10, 10)

WHY mirror = kite? Mirror karne se jodi wali side ke dono taraf same sides aati: padosi barabar. Ghumaane se saamne barabar: parallelogram.

Step 5: Kite + parallelogram = rhombus

Agar kite ki saamne sides bhi barabar ho jaayein (7 = 11?) to chaaron barabar → rhombus. Har rhombus kite hai, par har kite rhombus nahi.

Banana: diagonals d1 = 7 cm (AC) aur d2 = 10 cm (BD): AC ka beech O, wahan 90° pe BD, par O se B tak 3 cm, D tak 7 cm (koi bhi bantwaara). Siron ko jodo: kite!

🪜 Atak Gaye? Aise Socho

  • Pehle barabar sides pehchaano: kaunse do kone “barabar sides ke beech” hain? (B aur D)
  • Un dono kono ko jodne wali diagonal hi mirror line hai.
  • Mirror line doosri diagonal ko 90° pe aadha karti.
  • Mirror line ke dono taraf ke kone (A, C) barabar.
  • Area = d₁ × d₂ / 2 (rhombus jaisa, diagonals 90° pe).

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🔐 Deep Concept: Symmetry Hi Sab Kuch Hai

Kite ke saare gun ek hi baat se aate: BD ek mirror line hai. Mirror line ke dono taraf sab kuch barabar: sides, angles. Aur mirror line har “jodi” point (A aur C) ko jodne wali line ko 90° pe beech se kaat-ti. Yeh mirror ka niyam hai!

Rhombus se rishta: rhombus mein dono diagonal mirror lines hain (kyunki chaaron side barabar). Isliye rhombus mein dono diagonal kone aadhe karte, aur ek doosre ko aadha. Kite mein sirf ek.

Area ka formula bhi wahi: diagonals 90° pe → kite = 4 right triangles → area = d1d2/2, chahe O kahin bhi ho.

Unifying idea: jitni mirror lines, utne gun. Kite (1), rhombus (2), square (4). 🎯

sirf charumam.com readers ke liye 🔐

✏️ Solved Examples

Example 1 (Easy): Kite ABCD (BA = BC, DA = DC) mein ∠ABC = 80°, ∠ADC = 40°. ∠A aur ∠C?

∠A = ∠C. 2∠A = 360 − 120 = 240 → ∠A = ∠C = 120°.

Check: 80 + 120 + 40 + 120 = 360 ✅

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Example 2 (Medium): Kite mein AC = 12, BO = 8, OD = 5. Area aur BA?

BD = 13 → area = 12 × 13 / 2 = 78. AO = 6 → BA = √(36 + 64) = 10.

Check: do triangle ABC (12 × 8/2 = 48) + ADC (12 × 5/2 = 30) = 78 ✅

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Example 3 (NCERT style): Triangle (5, 7, 9) ki do copies jod ke kitne alag aakaar?

Har side (3) pe do tarah (mirror ya ghuma ke) → 6: 3 kite aur 3 parallelogram. (5 aur 7 wali side pe mirror karne se kite concave/dart banta, kyunki un sides ke ek sire pe ≈ 96° ka kona double hoke 180° se bada ho jaata.)

Check: mirror → padosi barabar (kite), ghuma ke → saamne barabar (parallelogram) ✅

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Dadaji ki baatein: “Upar ki taraf baandho” = kite mein mirror wali diagonal doosri ko beech se kaat-ti par khud beech se nahi kat-ti. “90° pe baandho” = mirror line hamesha 90° pe. Golu ki patang seedhi udi! 🪁✨

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🏠 Kite Aakaar Kahan?

  • 🪁 Patang: sabse mashhoor kite, 90° wale dande.
  • 🛡️ Purane dhaal (shield): kai kite aakaar ke.
  • 🦋 Titli ke pankh (ek jodi): lagbhag kite jaise symmetric.
  • 🏷️ Logo aur badge: “diamond” jaise kite shape.
  • 🔺 Teer ka sira (dart): concave kite, andar dhansa ek kona.

Jahan ek hi mirror line ho aur chaar kone, wahan kite chhupa hai.

— 📌 charumam.com

🧭 Kab Use Karein, Kab Nahi

SituationKya kareinKyun
Padosi sides ki do jodi barabar✅ KiteMirror line
Saamne sides barabar❌ Kite nahi (parallelogram)Sab barabar → rhombus
Diagonals 90°✅ Kite mein hameshaPar sirf ek aadha
Kone A = C✅ Mirror ke dono tarafB, D alag
Area✅ d₁ × d₂ / 2Diagonals se

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❌→✅ Worked Mistake

Sawaal: Kite ABCD (BA = BC, DA = DC) ke diagonals O pe milte hain. BD = 14. BO?

❌ Galat: “BO = 7, diagonals aadhe hote hain.”

✅ Sahi: kite mein BD, AC ko aadha karti, BD khud aadhi nahi hoti. BO tab tak nahi pata jab tak aur jaankari na ho. Check: patang ka chhota danda lambe ko beech se nahi kaat-ta ✅

Doosri common galti: ∠B = ∠D maan lena. Barabar ∠A = ∠C hain (mirror ke dono taraf), B aur D mirror pe hain.

🧠 Rule of thumb: Kite mein mirror wali diagonal (barabar sides ke beech ke kone jodne wali) doosri ko 90° pe aadha karti, khud nahi kat-ti.

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📝 10 MCQs

Q1. Kite ki paribhaasha?

(a) Padosi sides ki do jodi barabar
(b) Saamne sides barabar
(c) Sab angle 90°
(d) Ek jodi parallel
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Do jodi padosi: AB = BC, CD = DA ✅
  • (b) galat: Saamne barabar parallelogram hota.
  • (c) galat: Sab 90° rectangle hota.
  • (d) galat: Ek jodi parallel trapezium hota.

Q2. Kite ke diagonals?

(a) 90° pe
(b) Barabar
(c) Dono aadhe
(d) Parallel
Solution dekho

Sahi jawab: (a)

  • (a) sahi: SAS se ∠AOB = ∠COB = 90° ✅
  • (b) galat: Barabar hona zaroori nahi.
  • (c) galat: Sirf ek doosri ko aadha karti.
  • (d) galat: Diagonals hamesha kaat-te hain.

Q3. Kite mein kaunse kone barabar?

(a) Mirror ke dono taraf wale
(b) Mirror pe wale
(c) Sab
(d) Koi nahi
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Mirror ke dono taraf A aur C (SSS) ✅
  • (b) galat: B aur D alag ho sakte.
  • (c) galat: Sab barabar sirf square mein.
  • (d) galat: A = C to SSS se saabit hai.

Q4. ∠B = 100°, ∠D = 60° (B, D mirror pe). ∠A?

(a) 100°
(b) 100° aur ∠C = 100°
(c) 80°
(d) 60°
Solution dekho

Sahi jawab: (b)

  • (a) galat: ∠A akela 100°: aur ∠C bhi.
  • (b) sahi: (360 − 160)/2 = 100°, A = C ✅
  • (c) galat: 80° ka hisaab galat hai.
  • (d) galat: 60° to ∠D ka naap hai, ∠A ka nahi.

Q5. Kite ka area, diagonals 9 aur 14?

(a) 126
(b) 63
(c) 23
(d) 31.5
Solution dekho

Sahi jawab: (b)

  • (a) galat: Aadha karna bhool gaye.
  • (b) sahi: d₁d₂/2 = 9 × 14 / 2 = 63 ✅
  • (c) galat: Diagonals jod diye, galat.
  • (d) galat: Do baar aadha kar diya.

Q6. Har rhombus kite hai?

(a) Haan
(b) Nahi
(c) Sirf square
(d) Kabhi-kabhi
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Padosi sides ki jodi barabar ✅
  • (b) galat: Rhombus kite ki shart poori karta.
  • (c) galat: Har rhombus, sirf square nahi.
  • (d) galat: Hamesha, kabhi-kabhi nahi.

Q7. Triangle copy ko mirror karke jodne pe?

(a) Kite
(b) Parallelogram
(c) Trapezium
(d) Triangle
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Mirror → padosi sides barabar ✅
  • (b) galat: Ghumaane pe parallelogram banta.
  • (c) galat: Trapezium yahan nahi banta.
  • (d) galat: Do triangle se quadrilateral banta.

Q8. Kite + parallelogram dono ho to?

(a) Rhombus
(b) Rectangle
(c) Trapezium
(d) Koi nahi
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Padosi + saamne barabar → sab barabar ✅
  • (b) galat: Rectangle mein padosi barabar nahi.
  • (c) galat: Trapezium kite nahi hota aam taur pe.
  • (d) galat: Rhombus aisa hi hai, “koi nahi” galat.

Q9. Kite mein kitni symmetry lines?

(a) 0
(b) 1
(c) 2
(d) 4
Solution dekho

Sahi jawab: (b)

  • (a) galat: Ek to hai: mirror diagonal.
  • (b) sahi: Sirf mirror wali diagonal ✅
  • (c) galat: Do rhombus mein hoti hain.
  • (d) galat: Chaar square mein hoti hain.

Q10. Kite ki mirror diagonal doosri ko?

(a) 90° pe aadha
(b) Sirf 90°
(c) Sirf aadha
(d) Kuch nahi
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Perpendicular bisector: dono ✅
  • (b) galat: Aadha bhi karti hai, sirf 90° nahi.
  • (c) galat: 90° pe bhi hai, sirf aadha nahi.
  • (d) galat: SAS se dono gun saabit.

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❓ FAQs (Bachchon Ke Asli Sawaal)

1. Kite aur rhombus mein farak?

Rhombus mein chaaron side barabar; kite mein do-do. Rhombus = khaas kite.

2. Concave kite?

Haan, “dart” ya teer: ek kona andar dhansa. Gun same, bas ek diagonal bahar.

3. Kite parallelogram hai?

Aam taur pe nahi. Sirf jab rhombus ho.

4. Kite rectangle ho sakta?

Sirf square ke roop mein: rectangle + kite = square.

5. Kite ka perimeter?

2 × (a + b), a aur b do alag sides.

6. Kite ke angles ka jod?

360°, jaise har quadrilateral (Post 3 — Quadrilateral Ke Angles Ka Jod).

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🏋️ Practice Zone (12 Sawaal)

Q1. Easy Kite ki sides 5, 5, 9, 9. Perimeter?

Solution dekho

28. Check: 2 × (5 + 9) ✅

Q2. Easy Diagonals 8, 11. Area?

Solution dekho

8 × 11 / 2 = 44. Check: diagonals 90° → aadha rectangle ✅

Q3. Easy Kite ke diagonals ke beech angle?

Solution dekho

90°. Check: SAS saboot ✅

Q4. Easy ∠A = 110° (A, C mirror ke dono taraf). ∠C?

Solution dekho

110°. WHY: SSS se A = C.

Q5. Medium ∠B = 70°, ∠D = 50°. ∠A, ∠C?

Solution dekho

(360 − 120)/2 = 120° dono. Check: 70 + 50 + 240 = 360 ✅

Q6. Medium AC = 16, BO = 6, OD = 15. Sides?

Solution dekho

AO = 8: BA = √(64 + 36) = 10, DA = √(64 + 225) = 17. Check: 6-8-10, 8-15-17 ✅

Q7. Medium Kite mein ∠ABD = 35°. ∠ABC?

Solution dekho

70°. WHY: BD kone ko aadha karti. Check: 35 × 2 ✅

Q8. Medium Kite ka area 90, ek diagonal 12. Doosra?

Solution dekho

12 × d / 2 = 90 → 15. Check: 12 × 15 / 2 = 90 ✅

Q9. NCERT style Triangle 6, 6, 4 ki copies: kitne alag quadrilateral?

Solution dekho

6 wali side pe mirror → kite (6, 4, 4, 6); 6 pe ghuma → parallelogram (6, 4, 6, 4); 4 wali side pe → rhombus (6, 6, 6, 6), mirror aur ghuma dono same (isosceles symmetric hai). → 3 alag. Check: har ek ki sides gino ✅

Q10. NCERT style Kite mein ∠A = ∠C = 90°, BA = 3, AD = 4. BD?

Solution dekho

△BAD right: BD = 5. Check: 3-4-5 ✅

Q11. NCERT style Kya kite ke chaaron angle alag ho sakte?

Solution dekho

Nahi: A = C hamesha. Check: SSS ✅

Q12. NCERT style Rhombus ke ek diagonal pe kite ka gun dikhao.

Solution dekho

Rhombus ke dono diagonal mirror lines: har ek doosre ko 90° pe aadha karti. Check: kite gun dono taraf ✅

Answer Key — charumam.com exclusive

🧠 HOTS (Sochne Wale Sawaal)

Q1. Kite ki mirror diagonal BD = 20, AC = 10, O, BD ko 1 : 3 mein baant-ta. Sides?

Solution dekho

BO = 5, OD = 15, AO = 5 → BA = √50 ≈ 7.07, DA = √250 ≈ 15.8. Check: Pythagoras ✅

Q2. Kis triangle se mirror karke concave kite (dart) banta?

Solution dekho

Jab jodi wali side ke kisi sire ka angle 90° se bada ho: double hoke 180° se bada → dhansa kona. Check: obtuse triangle ✅

Q3. Kite ke kone ke bisectors ek point pe milte hain. Kyun?

Solution dekho

Kite ke andar ek circle fit hota (har side ko chhoota). Iska centre BD pe. Check: symmetry ✅

Q4. Kya kite mein ∠B = ∠D ho sakte?

Solution dekho

Haan, agar rhombus ho. Aam kite mein nahi. Check: rhombus mein saamne kone barabar ✅

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🏆 Olympiad Corner

Q1. Kite ABCD: BA = BC = 13, DA = DC = 20, AC = 24. BD?

Solution dekho

AO = 12: BO = 5, DO = 16 → 21.

Q2. Upar wale kite ka area?

Solution dekho

24 × 21 / 2 = 252.

Q3. Kite ke angles 60°, 60°, x, y (60 wale mirror ke dono taraf). x + y?

Solution dekho

240°.

Q4. Square ke ek kone ko kaat ke kya kite bana sakte?

Solution dekho

Haan: diagonal pe ek point chuno, use do saamne kono se jodo. Symmetry diagonal pe.

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💗 CharuMam Motivation

Golu ki patang ab sirf khilauna nahi, geometry ka lesson hai! Dadaji ki purani seekh ke peeche SSS aur SAS chhupe the. 🪁

Jab bhi aasmaan mein patang dekho, mirror line yaad karna. Maths aasmaan mein bhi udti hai! ☁️

— 📌 charumam.com

🟢 Master Recap

  • 💡 Chaabi: Kite = quadrilateral jisme padosi sides ki do jodi barabar: AB = BC aur CD = DA. Isse beech wali diagonal (BD) ek mirror line ban jaati: woh kone B, D ko aadha karti aur doosri diagonal ko 90° pe aadha.
  • Kite: padosi sides ki do jodi barabar.
  • Mirror diagonal kone aadhe karti (SSS).
  • Mirror diagonal doosri ko 90° pe aadha karti (SAS).
  • Mirror ke dono taraf ke kone barabar.
  • Area = d₁ × d₂ / 2.
  • Triangle copy: mirror → kite, ghuma → parallelogram.
  • Har rhombus kite hai.

— charumam.com 🎯

👉 Aage Kya?

Ab ek aisa aakaar jisme sirf ek jodi sides parallel hona kaafi hai: trapezium! Aur uska ek khaas roop, isosceles trapezium. Agle post mein. ⏢

Koi doubt? CharuMam AI Tutor se poochho, ya comment mein likho! 💬

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