Answer:
x≈7.5
Step-by-step explanation:
Part A:
Let's call the missing side of x:
5²+x²=9²
25+x²=81
x²=56
x= square root of 56
x≈7.5
Part B:
The sum of the internal angles of a triangle is always 180°, and the square in the top angle means that it is 90°, so:
90°+21°+y=180°
y=180°-90°-21°
y=69°
