Answer:

Explanation:
We are asked to find the measure of angle a. 
This triangle is a right triangle because of the small triangle in the corner representing a 90 degree or right angle. Therefore, we can use trigonometric functions. The three main functions are:
- sinθ=opposite/hypotenuse 
- cosθ= adjacent/hypotenuse 
- tanθ= opposite/adjacent 
The side measuring 6 is adjacent or next to angle a. The side measuring 9 is opposite angle a. Therefore, we will use the tangent function.


Since we are solving for an angle measure, we use the inverse trigonometric function. 



Round to the nearest tenth. The 0 in the hundredth place tells us to leave the 3 in the tenth place. 

The measure of angle a is approximately 56.3 degrees.