Question

Match the figures with their respective unknown angles.

• A. 80${}^{\circ }$
• B. 100${}^{\circ }$
• C. 40${}^{\circ }$

Answer 1

• The sum of all interior angles of a triangle is 180${}^{\circ }$.

So, $X={180}^{\circ }-({40}^{\circ }+{60}^{\circ })={80}^{\circ }$

• The exterior angle is equal to the sum of opposite interior angles.

So, $X={40}^{\circ }+{60}^{\circ }={100}^{\circ }$

• The angles opposite to the equal sides of an isosceles triangle are equal.

So, $X={40}^{\circ }$