Question

In $ABCD,m\angle A={120}^{0,}m\angle B={80}^{0,}m\angle C={45}^0$. Find $m\angle D$.

Answer 1

In quadrilateral $ABCD$

$\angle A={120}^{\circ },\angle B={80}^{\circ },\angle C={45}^{\circ }$

As we know

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

$⟹{120}^{\circ }+{80}^{\circ }+{45}^{\circ }+\angle D={360}^{\circ }$

$⟹\angle D={115}^{\circ }$