In the diagram PR is a tangent to the circle at... - WAEC Mathematics 2018 Question

In the diagram,

a = 50\(^o\) (alternate angles)

b\(_1\) + a 35\(^o\) = 180\(^o\) (sum of angles on a straight line)

i.e; b\(_1\) + 50\(^o\) + 35\(^o\)

= 180v

b\(_1\) + 180\(^o\) - 85\(^o\) = 90\(^o\)

But b\(_2\) = \(b_1\) = 95\(^o\) (angles in alternate segement)

<QST = b\(_2\) = 95\(^o\)