Work out the value of angle x, 90 degrees​

x = 45

Step-by-step explanation:

In isosceles triangles (a triangle where two sides are equal), the two base angles are congruent.

The sum of angles in a triangle is 180°.

In this problem, x is a base angle, so the other base angle is equal to x.

So, adding up all the measures of the angles in this triangle,

90 + x + x = 180

Simplify.

2x + 90 = 180

Substract 90 from both sides

2x = 90

Divide both sides by 2

x = 45

the first one, all those points on the line just make a strait line.