The angle between two altitudes of a parallelogram drawn from the vertex of an obtuse angle is $60^{\circ}$. Find the angles of the parallelogram.

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(N/A) Let the parallelogram be $ABCD$. Let $DP \perp AB$ and $DQ \perp BC$ be the two altitudes from the obtuse vertex $D$.
In quadrilateral $DPBQ$,the sum of the interior angles is $360^{\circ}$.
$\angle PDQ + \angle DPB + \angle B + \angle DQB = 360^{\circ}$
Given $\angle PDQ = 60^{\circ}$,$\angle DPB = 90^{\circ}$,and $\angle DQB = 90^{\circ}$.
$60^{\circ} + 90^{\circ} + \angle B + 90^{\circ} = 360^{\circ}$
$\angle B + 240^{\circ} = 360^{\circ}$
$\angle B = 360^{\circ} - 240^{\circ} = 120^{\circ}$.
Since opposite angles of a parallelogram are equal,$\angle D = \angle B = 120^{\circ}$.
Since consecutive interior angles are supplementary,$\angle A + \angle B = 180^{\circ}$.
$\angle A + 120^{\circ} = 180^{\circ} \Rightarrow \angle A = 60^{\circ}$.
Since opposite angles are equal,$\angle C = \angle A = 60^{\circ}$.
Thus,the angles of the parallelogram are $60^{\circ}, 120^{\circ}, 60^{\circ}, 120^{\circ}$.

Explore More

Similar Questions

Show that the quadrilateral formed by joining the mid-points of the sides of a rhombus,taken in order,is a rectangle.

Difficult
View Solution

$D$ and $E$ are the mid-points of the sides $AB$ and $AC$ respectively of $\triangle ABC$. $DE$ is produced to $F$. To prove that $CF$ is equal and parallel to $DA$,we need an additional information which is

Prove that a diagonal of a parallelogram divides it into two congruent triangles.

In quadrilateral $ABCD$,the angles are in the ratio $\angle A : \angle B : \angle C : \angle D = 2 : 4 : 5 : 7$. Find the measure of each angle of the quadrilateral and state the type of quadrilateral $ABCD$.

Points $P$ and $Q$ have been taken on opposite sides $AB$ and $CD$ respectively of a parallelogram $ABCD$ such that $AP = CQ$ (see figure). Show that $AC$ and $PQ$ bisect each other.

Vedclass Products

For Students

Vedclass Test Series

Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.

Start Free Trial
For Teachers

Exam Paper Generator

Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.

Try Free
For Institutes

Online Exam Module

Live online exams with unlimited students, 360° analytics & white-label branding.

See Demo