Explanation:
-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-
∠TAB = x°
∠TAC = 90°
(Angle between tangent and radius)
-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-
∠CAB = a = 90 - x
∠CBA = 90°
(Angle in a semi circle)
∠ACB = 180 - 90 - a (3ʳᵈ angle of triangle)
-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-'-
