Question

If sum of three angles in a quadrilateral is 270°, then what is the measure of the fourth angle?

• A. 270°
• B. 180°
• C. 360°
• D. 90°

Answer 1

The correct option is D 90°

Given, sum of three angles of a quadrilateral is 270°.

By angle sum property of a quadrilateral, sum of all the angles will be 360°.

So if, ABCD is a quadrilateral and
$\angle$ABC + $\angle$BCD + $\angle$CDA = 270° ...(i)

By angle sum property,
$\angle$ABC + $\angle$BCD + $\angle$CDA + $\angle$ DAB = 360°
$\to$ 270° + $\angle$DAB = 360° (from (i))
$\to$ $\angle$DAB = 360° - 270° = 90°.

So, the fourth angle is 90°.