Triangle XYZ is an isosceles triangle with sides XY = XZ. If the measure of angle Y is 80°, what is the measure of angle X?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 20.
Given that, triangle XYZ is an isosceles triangle with XY = XZ
Angle Y = 80°
Sum of all the angles of a triangle is 180°.
In an isosceles triangle, the angles opposite to the equal sides are equal in measure.
According to the given question,
In triangle XYZ, Angle Y = angle Z = 80°
And, Angle X + Angle Y + Angle Z = 180°
⇒ Angle X + 80° + 80° = 180°
⇒ Angle X = 180° - 160°
⇒ Angle X = 20°