Answer:
The correct answer is option c. 17.9°
Explanation:
From the figure we can see that a right angled triangle RST.
Right angled at T
To find the value of R
It is given that,
r=10 and s=31
Tan R = Opposite side/Adjacent side
Tan R = ST/SR = r/s = 10/31 = 0.3225
R = Tan⁻¹(0.3225) = 17.87 ≈ 17.9°
Therefore the correct answer is option c. 17.9°