ABCD is a cyclic quadrilateral such that AB is the diameter of the circle and ∠ADC = 145°, then what is the measure of ∠BAC?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e 55°.

As one knows that the sum of the opposite angle in a cyclic quadrilateral is 180°.
So ABC = 180 - 145 = 35°
One also knows that the sum of the angle in a semicircle is 90°.
So ACB = 90°.
The sum of the interior angle of a triangle is 180°.
∠BAC = 180 - 90 - 35 = 55°