The figure shows a parallelogram ABCD. The bisectors of angles A,B,C,D enclose a quadrilateral PQRS. Using the exterior angle theorem prove that each angle of quadrilateral PQRS is a right angle.
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Step-by-step explanation:
Given :-
The figure shows a parallelogram ABCD. The bisectors of angles A,B,C,D enclose a quadrilateral PQRS.
To find :-
Using the exterior angle theorem prove that each angle of quadrilateral PQRS is a right angle.
Solution :-
Given that
ABCD is a Parallelogram
The bisectors of angles A,B,C,D enclose are AP, BR ,CS ,DQ respectively enclose a quadrilateral PQRS
We know that
The adjacent angles are supplementary in a Parallelogram
=> <A+ <D = 180°
On dividing by 2 both sides then
=> <A/2 + <D/2 = 180°/2
=> <PAD + < PDA = 90° ---------(1)
Now,
In ∆ DPA , AP is extended to S then
The exterior angle DPS is equal to the sum of opposite two interior angles
=> < DPS = <PAD + < PDA
=> < DPS = 90° (from (1))
=> < DPS = <SPQ = 90° -------(2)
Since Vertically opposite angles are equal.
Similarly we can find
< PQR = 90° -----------(3)
<QRS = 90° ----------(4)
<RSP = 90°----------(5)
From (2),(3),(4)&(5)
Each angle in PQRS quadrilateral is equal to 90°
Hence, Proved.
Used formulae:-
- The adjacent angles are supplementary in a Parallelogram
- The exterior angle is equal to the sum of opposite two interior angles
- Vertically opposite angles are equal.
Answer:
To prove :-
- Using exterior angle theorem prove that each angle of quadrilateral PQRS is a right angle .
Proof:-
- Here given that
- ABCD is a parallelogram
- The bisectors of right angle ABCD encloses are AP,BR , CS,DQ respectively. encloses a quadrilateral PQRS.
- We know that,
- The adjacent angles are supplimentary in a Parallelogram.
- <A+<D=180degree.
- On dividing both sides we get,
- <PAD+<PDA=90degree
- The exterior angles DPS is equal to the sum of opposite two interior angles.
- <DPS=<PAD+<PDA
- <DPS= 90 degree (ii)
- We know that vertical opposite angles are equal.
- <PQR=90degree (3)
- <QRS=90degree (4)
- <RSP=90degree (5)
- From 2,3,4,5
- Each angle in PQRS quadrilateral is equal to 90 degree.