Can someone help me with this?

Question

asked Aug 3, 2021 112k views

1 Answer

Mintgreen · Answer 1 · 2021-08-08T15:21:51+0000

Answer:

∠ A = 72°

Explanation:

The sum of the 3 angles in a triangle = 180°, thus

∠ ECD = 180° - (90 + 54)° = 180° - 144° = 36°

∠ ACB = ∠ ECD = 36° ( vertical angles )

Since AC and BC are congruent then Δ ABC is isosceles, thus the base angles are congruent, that is

∠ A = ∠ B

∠ A =
(180-36)/(2) =
(144)/(2) = 72°