Question

If the sides of the parallelogram and an included angle are 6, 10 and 100 degrees respectively, find the length of the larger diagonal.

Answer 1

let a=6, b=10, diagonal =d

$d^2=a^2+b^2-2abcos100^o=6^2+10^2-2\times6\times 10 cos100^o$

$d^2=36+100+20.76=156.76$

$d=\sqrt{156.76}=12.52$