To find height $ h $ use Pythagorean Theorem:
$$ h^2 + \frac{ d^2 }{ 4 } = e^2 $$After substituting $ d = 26 $ and $ e = 85 $ we have:
$$ h ^ {\,2} + \frac{ 26^2 }{ 4 } = 85^2 $$ $$ h ^ {\,2} + \frac{ 676 }{ 4 } = 85^2 $$ $$ h ^ {\,2} + 169 = 85^2 $$ $$ h ^ {\,2} = 7225 - 169 $$ $$ h ^ {\,2} = 7056 $$ $$ h = \sqrt{ 7056 } $$$$ h = 84 $$