Question

Find the value of x.

Answer 1

The sum of all angles in a triangle is always 180°. Our triangle has 2 equal angles and one 40° angle. That means that the size of those two angles is (180° - 40° ) / 2 = 70°. Then from 180° or half circle subtract 70° and you will end up with 110° which the value of x.

Hope this helps.

r3t40

Answer 2

The two angles other than 40° in the triangle are same so let us name it y.

Now, sum of interior angles of a triangle is 180°

Therefore,

40 + y + y = 180

40 + 2y = 180

2y = 180 - 40

2y = 140

y = 140/2

y = 70

Now x = 180 - y ( linear pair )

x = 180 - 70

x = 110°