ABCD is cyclic quadrilateral such that AB is the diameter of the circle circumscribing it and ∠ADC = 145º. What is the measure of ∠BAC?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 55º
AB is the diameter,
∴ ∠ACB = 90º
As, ABCD is a cyclic quadrilateral,
∴ ∠ADC + ∠ABC = 180º
⇒ ∠ABC = 180º - 145º = 35º
Now, in the triangle ABC,
∠BAC = 180º - (90º + 35º) = 55º