Find the diagonal of a rectangle whose two sides are 15 and 5√7.

The diagonal of a rectangle and its two sides (length and width) form a right-angled triangle. Moreover, the diagonal of the rectangle will be the hypotenuse of the triangle (we denote it by d), and the length and width are the legs. To find the diagonal of a rectangle, apply the Pythagorean theorem for a triangle: The square of the hypotenuse is equal to the sum of the squares of the legs.

d ^ 2 = 15 ^ 2 + (5√7) ^ 2;

d ^ 2 = 225 + 25 * 7;

d ^ 2 = 225 + 175;

d ^ 2 = 400;

d = √400;

d = 20.

Answer. twenty.