Question

Can someone please solve this ASAP?

Answer 1

The ladder and the wall form a right triangle.
The length is the hypotenuse = 15.
The base = 2*(15/5) = 2*3 = 6

Use pythagorean theorem to find other side of triangle:
$a^2 + b^2 = c^2 \\ \\ a^2 + 6^2 = 15^2 \\ \\ a^2 + 36 = 225 \\ \\ a^2 = 189 \\ \\ a = \sqrt{189} = 3 \sqrt{21}$