<u>Answer:</u>
A building makes a
angle with the ground .The two interior angles are
and ![20^{\circ}](https://tex.z-dn.net/?f=20%5E%7B%5Ccirc%7D)
<u>Solution: </u>
Given, a ladder which is against the building wall makes an exterior angle of ![110^{\circ}](https://tex.z-dn.net/?f=110%5E%7B%5Ccirc%7D)
And building makes a
angle with the ground.
So, altogether it makes a right angle triangle with ladder as hypotenuse and ground as base leg and building as another leg.
Now, we know that, sum of exterior angles and interior angles equals to ![180^{\circ}](https://tex.z-dn.net/?f=180%5E%7B%5Ccirc%7D)
Here, in the case of ground and ladder, exterior angle is
and interior angle is unknown.
Exterior angle + interior angle = 180
110 + interior angle = 180
Interior angle = 180 – 110
Interior angle = ![70^{\circ}](https://tex.z-dn.net/?f=70%5E%7B%5Ccirc%7D)
We have found one of the two interior angles of right angle triangle.
We know that, sum of angles in a triangle is 180 degree
Known Interior angle + unknown interior angle + right angle = 180
70 + unknown interior angle + 90 = 180
Unknown interior angle + 160 = 180
Unknown interior angle = 180 - 160
Unknown interior angle = ![20^{\circ}](https://tex.z-dn.net/?f=20%5E%7B%5Ccirc%7D)
Hence the two interior angles are
and ![20^{\circ}](https://tex.z-dn.net/?f=20%5E%7B%5Ccirc%7D)