Question

A 15 m long ladder reach a window 12 m high from the ground on placing it against a wall at a distance a find

Answer 1

pythogorus thm;
${a}^{2} + {12}^{2} = {15}^{2}$
${15}^{2} - {12}^{2} = {a}^{2}$
$225 - 144 = {a}^{2}$
${a}^{2} = 81$
$a = 9$