Question

If line AD is a tangent to circle B at point C, and m∠ABC = 55º, what is the measure of ∠BAD?

135º
100º
145º
155º

Answer 1

The correct answer is 145.

Explanation:

I took the quiz and it was right

Answer 2

The tangent AD at point C forms a right angle to circle B, such as ∠ACB=90° and ∠ABC=55°.

We also know that the summation of all angles in a triangle is 180°. Thus we have the expression below:
180°=∠ABC + ∠ACB + ∠BAD
180°=55°+90°+∠BAD
∠BAD=35°

Therefore, the answer is 35°.