Question

Find the value of x.

Answer 1

its an isosceles triangle. you know its other internal angles...

Answer 2

The triangle is isosceles. The two unknown angles must be equal to one another and the interior angles in the triangle must add up to 180 degrees, so each of the two unknown angles in the triangle is 70 degrees. Now, you know that x and one of the interior angles of the triangle are supplementary angles. They also add up to 180 degrees. That should enable you to determine x.

Answer 3

let the base angles be Z and Y
Z=Y as base angles of an isosceles triangle are equal
Z+Y+40= 180 degree as it is the sum of a triangle
Z=Y, hence Z+Z+40=180
Z= 70
Z+X=180 as they are angles on a straight line whose sum is 180
Z=70
hence, X=180-70= 110 degrees