Question

Two angles of a triangle are $30°$ and $90°$. So, the third angle is:

• A. $90°$
• B. $60°$
• C. $40°$
• D. $50°$

Answer 1

The correct option is B

$60°$

Explanation for the correct answer:

Find the third angle:

Let the third angle be $x$.

We know from the angle sum property of the triangle.

Sum of all interior angles of a triangle is $180°$.

$\Rightarrow$$x+30°+90°=180°$

$\Rightarrow$ $x=180°-120°$

$\Rightarrow$ $x=60°$

Therefore, the required angle will be $60°$.

Thus, the option (B) is correct.