Answer:
16.5 cm
Step-by-step explanation:
Using Pythagoras' identity in the right triangle
The square on the hypotenuse is equal to the sum of the squares on the other 2 sides.
let x be the other leg, then
x² + 13² = 21²
x² + 169 = 441 ( subtract 169 from both sides )
x² = 272 ( take the square root of both sides )
x = [tex]\sqrt{272}[/tex] ≈ 16.5 cm ( to the nearest tenth )
