Answer:
(a) ∠DAB = 59°
(b) ∠A = 135°
(c) ∠A = 99°
Step-by-step explanation:
<u>Theorem</u>: If a quadrilateral is inscribed inside a circle, then the opposite angles of the quadrilateral are SUPPLEMENTARY.
So, here in the given figures:
(1) ∠DCB + ∠DAB = 180° (as opposite angles are supplementary)
⇒∠DAB = 180° - 121° = 59°
or, ∠DAB = 59°
(2) ∠DCB + ∠DAB = 180° (as opposite angles are supplementary)
⇒(3x+6) + (x+2) = 180° or, 4x = 180 - 8 = 172
⇒ x = 172/4 = 43, or x = 43
So, ∠A = (3x+6) = 3(43) + 6 = 135°
(3) (28) + (x) = 180°
or, x = 180 - 28 = 152
So, ∠A = (x- 36) = 135 - 36 = 99°
(4)