How can you check the correctness of a division answer that has no remainder?

Multiply the quotient and dividend to get the divisor

To be a right angled triangle, it must follow the rule a² + b² = c² (where c is the longest side)

4.5² + 6² = 20.25 + 36 = 56.25
7² = 49
This is NOT a right angled triangle.

To make this into a right angled triangle, the longest side c should be longer. 
c = √56.25 = 7.5 inches