Question
In a regular pentagon ABCDE, Inscribed in a circle; find ratio between angle EDA and angle ADC.
✓
Answer
Arc AE subtends ∠AOE at the centre and
∠ADE at the remaining part of the circle.
$\therefore \angle ADE =\frac{1}{2} \times 72^{\circ}$
= 36 (central angle is a regular pentagon at O)
∠ADC = ∠ADB + ∠BDC
= 36° + 36° + 72°
∴ ∠ADE : ∠ADC = 36° : 72° = 1: 2
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