Question

How do I solve this to find B??

Answer 1

Check the picture below.

let's recall that a triangle has a sum of interior angles to be 180°.

so if triangle PQR has two equal sides and one angle of 60°, then all angles are really 60° and all sides are equal as well, so is an equilateral triangle.

if triangle PSR has two equal sides and one angle of 90°, then the other two twin angles are 45° each.