As you can see, this is a right triangle, meaning you have the Pythagorean Theorem at your disposal!
This simply means that a² + b² = c², in which c is the hypotenuse and a and b are the adjacent sides. You have the hypotenuse, which is seven, and one of the adjacent sides, which is 6, so if you substitute them into the equation, you get:
6² + b² = 7²
Evaluate to get:
36 + b² = 49
If you subtract 36 from both sides, you get that b² = 13. So the answer is the square root of 13, which is approximately 3.61, or letter B.
Hope this helps!
