Step-by-step explanation:
We know:
The sum of the measures of acute angles in a right triangle is equal 90°.
Therefore
(1) A + B = 90°
(2) 90° + B + C = 180° - angles on a straight line
(3) from (2) B + C = 90° → B = 90° - C
(4) from (1) and (3) A + (90° - C) = 90° → A - C = 0
Therefore
A = C → ∠A ≅ ∠C
