Answer:
7.5 cm
Step-by-step explanation:
it is a right triangle, b=10, hypotenuse c=12.5
a^2+b^=c^2 the Pythagorean theorm
a^=c^2-b^2
a^2= 12.5^2-10^2
= 56.25
a=√56.25=7.5 cm
