Practicing Success
In a circle with center O, AB is the diameter and CD is a chord such that ABCD is a trapezium. If ∠BAC = 30°, then ∠CAD is equal to? |
120° 30° 60° 110° |
30° |
In ΔACB ∠ACB = 90° (angle in semicircle) ∠ABC = 90° - 30° = 60° ∠ADC = 120° (cyclic quad.) ∠DCA = ∠CAB = 30° (alternate angle) ∠CAD = 180° - (120° + 30°) = 30° |