In ΔABC, D is a point on side BC such that ∠ADC = 2∠BAD. If ∠A = 80° and ∠C = 38°, then what is the measure of ∠ADB?
In ΔABC, D is a point on side BC such that ∠ADC = 2∠BAD. If ∠A = 80° and ∠C = 38°, then what is the measure of ∠ADB? Correct Answer 56°
Given:
In ΔABC, D is a point on side BC
∠ADC = 2∠BAD
∠A = 80° and ∠C = 38°
Concept used:
The sum of all angles in any triangle is to be 180°
The sum of two opposite angles = external angles
Explanation:
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According to the question,
80° + 38° + ∠B = 180°
⇒ ∠B = 62°
∵ ∠ADC = 2∠BAD
if ∠BAD = x than ∠ADC = 2x
By theorm,
∠BAD + ∠ABD = ∠ADC
⇒ x + 62° = 2x
⇒ x = 62°
In ΔABD,
∠ABD + ∠BAD + ∠ADB = 180°
⇒ 62° + 62° + ∠ADB = 180°
⇒ ∠ADB = 56°
∴ The measure of ∠ADB is 56° .
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Feb 20, 2025