Question

(b) ADB = ADC = 90°​

Answer 1

Step-by-step explanation:

∠ADB=∠ADC (corresponding parts of the congruent triangles ) ...(1)

Now, ∠ADB+∠ADC=180

o

[∵∠ADB and ∠ADC are on the straight line]

⇒∠ADB+∠ADB=180

o

[from(1)]

⇒2∠ADB=180

o

⇒∠ADB=

2

180

o

=90

o

∴∠ADB=∠ADC=90

o

[from (1)]