3 part question-Show work for part a and part c

Answer:
Step-by-step explanation:
Part A: You can only use Pythagorean's Theorem on a right triangle.
Part B: The side across from the right angle is the hypotenuse. It has a length of 15.
Part C: To find the missing side using Pythagorean's Theorem:
[tex]a^2+11^2=15^2[/tex] and
[tex]a^2+121=225[/tex] and
[tex]a^2=104[/tex] and
a = 10.20