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Calculate ∠AOC ,∠BOD and ∠AOE in the adjoining figure it is being given that ∠COD=90°,∠BOE=72° and AOB is a straight line.​

Answer»

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Calculate ∠AOC ,∠BOD and ∠AOE in the adjoining figure it is being given that ∠COD=90°,∠BOE=72° and AOB is a straight line.

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Since AOB is a straight line, the SUM of all the angles on the lower SIDE of AOB at a POINT O on it, is 180°.

∴ ∠AOE + ∠BOE = 180°

⟹<klux>3X</klux> + 72 = 180

⟹ 3x = (180 - 72) = 108 ⟹ x =  \frac{108}{3} = 36. \\

Again, AOB is a straight line and O is a point on it.

So, the sum of all angles on the UPPER side of AOB at a point O on it, is 180°.

∴ ∠AOC + ∠COD + ∠DOB = 180°

=  > x + 90 + y = 180

⠀[∴ ∠AOC=x°,∠COD=90° and ∠DOB=y°]

⟹ 36 + 9 + y = 180 \:  \:  \: [\therefore \: x = 36] \\

⟹ 126  + y = 180 ⟹ y = (180 - 126) = 54. \\

∴ ∠AOC = x° = 36°,∠BOD=y° = 54°,

∠AOE=(3x)° = (3×36)° = 108°.

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