solution of the questions The sides of a quadrilateral ABCD are 6 cm, 8 cm, 12 cm and 14 cm (taken in order) respectively, and the angle between the first two sides is a right angle. Find its area.

Answer 1

use Heron's formula.

draw a line from the end of the 6 and 8 cm side, forming a right triangle. The length of that is 10 cm (Pythagorean)

Now you have two triangles. Figure the area of each using Heron's formula,then add them.
semiperimert s=1/2 (a+b+c) on each triangle

Area=sqrt[(s-a)(s-b)(s-c)s] HERO's formula

do that for both triangles, then add.