In the figure AB = 11cm, BC = 8cm, AD = 3cm, AC = 5cm and DAC is a right angle.

Question

The size of ADC;

The size of ACB;

The area of the quadrilateral ABCD.

Answer 1

tan ADC = 5/3
11^2 = 5^2+8^2 - 2*5*8 cos ACB
Now you can figure the areas of the triangles ACD and ACB, and just add them up for the area of ABCD

Answer 2

So aera =1/2(AB)(BC)sin(ACB)