Question

Three angles of quadrilaterals are 85${}^{\circ }$, 60${}^{\circ }$ and 75${}^{\circ }$, then the fourth angle is______.

• A. 160°
• B. 140°
• C. 105°
• D. 120°

Answer 1

The correct option is B

140°

Given, $\angle$ A = 85${}^{\circ }$, $\angle$ B = 60${}^{\circ }$, and $\angle$ C = 75${}^{\circ }$

We know that, the sum of all the angles of quadrilaterals is 360${}^{\circ }$

$\angle$ A + $\angle$ B + $\angle$ C + $\angle$ D = 360${}^{\circ }$

$\Rightarrow$ $\angle$ D = (360${}^{\circ }$ - 85${}^{\circ }$ - 60${}^{\circ }$ - 75${}^{\circ }$) = 140${}^{\circ }$