Answer:
C
Step-by-step explanation:
In a right triangle, the side opposite the right angle is the largest side as the right angle represents the largest angle in the triangle. Therefore, as 17.5 is opposite the right angle, we can say that AB²+10²=17.5², and √(17.5²-10²)=AB = 14.4
Using sohcahtoa, we can establish that
sin(∠C) = opposite/hypotenuse = 14.4/17.5, and
arcsin(14.4/17.5) = ∠C = 55°
Because the angles in a right triangle add up to 180 degrees, we can say that ∠A+∠B+∠C = 180°, so ∠A + 90 + 55 = 180 and ∠A = 35°
