Multiply the above two formulas:

(cosA*sinA )/(cosBsinB)= 1

cosA*sinA =cosBsinB

Sin2a = sin2B and 2B are both greater than 0.

2A=2B or 2A=π-2B

So A=B or A+B=π/2.

Triangle ABC is an isosceles triangle (A=B) or a right triangle (C=π/2).