Work out the unknown angles. give reasons for each answer.

A)

Because the sum of angles in a triangle must equal 180° we can say:

62+α+90=180

α+152=180

α=28°

b)

Since all sides have equal length, all angles must have equal measure.  (This is an equilateral triangle).  And again, because the sum of the angle must be 180° we can say:

b+b+b=180

3b=180

b=60°