Question

The information given represents lengths of sides of a right triangle with c the hypotenuse. Find the correct missing length to the nearest hundredth. A calculator may be helpful.

a = ?, b = 13, c = 21
a 15.83
b 15.87
c 16.19
d 16.49

Answer 1

a = ?, b = 13, c = 21
21^2=a^2+13^2
441=a^2+169
441-169=a^2
272=a^2 taking sqrt on both sides 
=16.49
option d is right
hope this helps

Answer 2

a² = c² - b²
a² = 21² - 13 ²
a² = 441 - 169
a² = 272
a = √272 = 16.49242 ≈ 16.49
Answer : D ) 16.49