Answer:
81 degrees
Step-by-step explanation:
A quadrilateral has four interior angles which sum up to 360 degrees.
As we are given that two angles are right angles which means the sum of two angles will be 180 degrees and the third angle is 99 degrees.
As we know that the four angles sum up to 360 degrees.
Let A,B,C and D denote the four angles,
Then
Sum of angles = 360
A+B+C+D=360
90+90+99+D=360
279+D=360
D=360-279
D= 81 degrees
So the fourth angle is 81 degrees ..
15
19
14
0 because they cancel out :D
A linear pair are two given angles whose sum is equal to .
Let the exterior angle be represented by , and the three interior angles of the triangle be represented by , and .
Assume that the vertex angle is the linear pair to the exterior angle .
i.e + = (sum of angles on a straight line)
Thus,
i. + = (sum of two opposite interior angles is equal to an exterior angle)
⇒ = -
Also,
= -
But,
+ + = (sum of angles in a triangle)
⇒ = - ( + )
and
+ = -
ii. + + = (sum of angles in a triangle)
= - ( + )
+ =