Question

How to do this? I don’t know how to find the answer please help me

Answer 1

The answer is 20.
(25^2 - 15^2)^.5 = 20


Step-by-step explanation:
It's a use of the Pythagorean theorem. DC is a leg of a right triangle. You know the length of the other leg and the hypotenuse.

Answer 2

20 cm

Step-by-step explanation:

Pythagoras theorem states that a² + b² = c². But what does this actually mean? First of all we need to recognise that it only works in right-angled triangle. If I put the values in you would a² + 15² = 25². So we have to solve for "a". A = DC

a² + 15² = 25²

→ Minus 15² from both sides to isolate a²

a² = 25² - 15²

→ Work out 25² - 15²

a² = 400

→ Square root both sides to isolate a

a = 20