What is the measure of ∠R?

Answer:
Step-by-step explanation:
Triangle RST is a right angle triangle.
From the given right angle triangle,
RS represents the hypotenuse of the right angle triangle.
With m∠R as the reference angle,
RT represents the adjacent side of the right angle triangle.
ST represents the opposite side of the right angle triangle.
To determine m∠R, we would apply
the cosine trigonometric ratio.
Cos θ = adjacent side/hypotenuse. Therefore,
Cos R = 8/10 = 0.8
m∠R = Cos^0.8
m∠R = 36.9° to the nearest tenth.