What is the measure of missing angle indicated?

∠acb = 8°

step-by-step explanation:

∠xba lies on the circle and is half the measure of the intercepted arc ax

hence

measure of arc ax = 2 × 42° = 84°

∠acb is outside the circle and is

∠acb = (arcab - arcax ), hence

∠acb = 0.5 (100 - 84) = 0.5 × 16° = 8°

isn't it a pentagon? sense [3 (triangle) + 4 (rectangle)] - 2 (triangle and rectangle connected) = 5 (pentagon)