Hey there!!
Important concepts to remember:
- The value of an exterior angle is equal to the sum of the opposite interior angles.
- The value of the base angles in an isosceles triangle are equal.
- The total sum in a triangle is 180°.
Keeping all this in mind:
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Let's take the base angle as 'y'
Then, the angles in this triangles would be :
... y , y , 40
Their sum would be 180°
... y+y+40=180
... 2y+40=180
... 2y=180-40
... 2y=140
... y=140/2
... y=70
Hence, the base angles are 70°
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Now, the value of x° = 40 + 70
Hence, the value of x° is 110°
We could also find this by using linear pair:
...The base angle and the angle 'x' form a linear pair.
Hence,
... x + 70 = 180
... x = 180 - 70
... x = 110°
Hence, the value of x is 110.
Hope this helps!
