Question

If two angles in a triangle are ${65}^{\circ }$ and ${85}^{\circ }$, then the third angle is:

• A. ${30}^{\circ }$
• B. ${45}^{\circ }$
• C. ${60}^{\circ }$
• D. ${90}^{\circ }$

Answer 1

The correct option is A ${30}^{\circ }$

As we know that the sum of the angles in a triangle $=$ ${180}^{\circ }$
Given two angles are ${65}^{\circ }$ and ${85}^{\circ }$
$\Rightarrow {65}^{\circ }+{85}^{\circ }+x^{\circ }={180}^{\circ }$
$\Rightarrow x+{150}^{\circ }={180}^{\circ }$
$\Rightarrow x={180}^{\circ }-{150}^{\circ }$
$\therefore x={30}^{\circ }$
Hence, third angle $=$ ${30}^{\circ }$