Question Analysis
This question focuses on using inverse trigonometric functions to find the measure of angle in a right - triangle. We must identify the appropriate trigonometric ratio based on the side lengths relative to angle and then use the inverse function to calculate the angle.
Key Concept Explanation
In a right - triangle, for an acute angle :
, , .
Inverse trigonometric functions , , are used to find the angle when the ratio of the sides is known. For example, if , then ; if , then