Question

An angle of a right-angled triangle is ${40}^0$, what is the third angle?

• A. ${60}^0$
• B. ${40}^0$
• C. ${80}^0$
• D. ${50}^0$

Answer 1

The correct option is D

${50}^0$

One of the angles of a right angled triangle is ${90}^0$ and the other is given as ${40}^0$.
Sum of the angles of a triangle is ${180}^0$.
Let the unknown angle be $x$.
$x+{40}^0+{90}^0={180}^{0}x+{130}^0={180}^{0}x={180}^0-{130}^0={50}^0$
Unknown angle $={50}^0$