Question for Brainly Stars and Mods
Mathematics
Class 9th
Lines and Angles
Question- In fig 6.13 , lines AB and CD intersect at O . if angle AOC + angle BOE = 70° and angle BOD = 40° , then find angle BOE and reflex angle COE .
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Answers
Step-by-step explanation:
∠AOC + ∠BOE = 70⁰
∠AOC + ∠COE + ∠BOE = 180°
[linear pair]
So,
if ∠AOC + ∠BOE = 70°
→ 70° + ∠COE = 180°
∠COE = 180-70
∠COE = 110⁰
∠BOD = ∠AOC [ Vertically Opposite Angles]
Now,
→ ∠AOC + ∠COE + ∠BOE = 180°
→40° +110° + BOE = 180°
→150° + BOE = 180°
→∠BOE = 180° - 150⁰
→∠BOE = 30°
∠BOD + ∠DOA = 180° [Liner Pair]
→40° + DOA = 180°
→∠DOA = 180° - 40°
→∠DOA = 140°
Hence,
reflex angle (COE) = <AOC + <DOE + ZBOD + ZBOE
reflex angle (∠COE) = 40° +140° +40° +30°
reflex angle (∠COE) = 250⁰
Solution :
➣ To Find :
- ∠BOE
Since,
∠ AOC + ∠ BOE = 70°
We know,
- Angles along straight line = 180°
So,
∠AOC + ∠BOE + ∠COE = 180°
⇒ 70° + ∠COE = 180°
⇒ ∠COE = 180° - 70°
∴ ∠COE = 110°
➣ Given :
- ∠ BOD = 40°
Linear Pair = 180° ( COD )
∠ COE = 110°
So,
∠COE + ∠BOE + ∠BOD = 180°
⇒ 110° + ∠BOE + 40° = 180°
⇒ 150° + ∠BOE = 180°
⇒ ∠BOE = 180° - 150°
∴ ∠BOE = 30°
➣ Reflex ∠COE :
Here,
- Reflex ∠COE =
∠COA + ∠AOD + ∠BOD + ∠BOE
Since,
∠BOE = 30° and
∠AOC + ∠BOE = 70°
⇒ ∠AOC = 70° - 30°
∴ ∠AOC = 40°
➣ Finding ∠AOD :
∠BOD + ∠AOD = 180° (linear pair)
⇒ 40° + ∠AOD = 180°
⇒ ∠AOD = 180° - 40°
∴ ∠AOD = 140°
☆ Putting Values :
⇒ 40° + 140° + 40° + 30° = Reflex ∠COE
∴ Reflex ∠COE = 250°
- Question :
Find
- ∠BOE
- Reflex ∠COE
➩ ∠BOE = 30°
➩ Reflex ∠COE = 250°