Question

the side of rectangle are 80 and 18 respectively the length of diagonal is

Answer 1

applying Pythagoras theorem
length of diagonal=square root of [l(square)+b(square)]
so u will get 82

Answer 2

$length = 80\\ breadth = 18 \\ diagonal = \sqrt{ {length}^{2} + {breadth}^{2} } \\ \sqrt{ {80}^{2} + {18}^{2} } \\ \sqrt{6400 + 324} \\ \sqrt{6724 } \\ \sqrt{82 \times 82} \\ 82$