Rini used a stick to draw a right triangle in the ground. the hypotenuse of her triangle is 24 inches and one of the legs is 12 inches. what is the length of the third side? round to tenth if necessary.

Use the pythagorean theorem A² + B² = C²

A and B are legs and C is the hypotenuse 

so-    A² + 12² = 24²      A² + 144 = 576  
                                           -144     -144

                                   A² = 432          then you have to take the square root 
                                                           of each side 

so-      A = √432    or aprox. 20.78