Answer:
c=13 and a=20
Explanation:
Here you need to use the Pythagoras theorem :
c²=a² + b²
c = √a² + b²
c = √(12)²+(5)²
c= √144+25
c = √169
c = 13
2) c²=a²+b²
b= √c²-b²
b= √(29)²-(21)²
b = √400
b = 20
In 2 you change your formula just so that it can be easier and just calculate your length straight forward but you can also just do it in the original equation