Question

What is the measure of R? A 30° B 45° C 60° D 80° ​

Answer 1

B

Explanation:

since RS = TS then Δ RST is isosceles with base angles congruent, that is

∠ R = ∠ T

the sum of the 3 angles is 180°

∠ R + ∠ T + 90° = 180 ( substitute ∠ T = ∠ R )

∠ R + ∠ R + 90° = 180° ( subtract 90° from both sides )

2 ∠ R = 90° ( divide both sides by 2 )

∠ R = 45°