Answer
Verified
395.1k+ views
Hint: A quadrilateral is a polygon having four sides and four vertices. A quadrilateral is cyclic when all of its vertices lie on a circle.
A cyclic quadrilateral is given by the following figure:
A quadrilateral formed by the internal angle bisectors of a quadrilateral ABCD is PQRS:
We need to prove PQRS is cyclic.
A rule of angle equality is, vertically opposite angles are equal.
Angle sum property of a triangle gives the sum of all angles of a triangle = ${180^0}$
To prove the quadrilateral PQRS is cyclic, it is enough to prove that the sum of opposite angles of PQRS is ${180^0}$ . Implies $\angle SPQ + \angle SRQ = {180^0}$
Complete step-by-step answer:
Step 1: Consider a quadrilateral ABCD with internal bisectors AQ, BS, CS, DQ of angles $\angle A$, $\angle B$ , $\angle C$ and $\angle D$ respectively. We need to prove the quadrilateral PQRS formed by these four internal angle bisectors is cyclic.
As vertically opposite angles are equal, we obtain the following equalities:
$
\angle SPQ = \angle APB \\
\angle SRQ = \angle DRC \\
$
Adding above two formulas we get $\angle SPQ + \angle SRQ = \angle APB + \angle DRC$
As AQ is the angle bisector of $\angle A$ and P is a point on AQ, By angle sum property,
$\angle APB = 180 - (\dfrac{1}{2}\angle A + \dfrac{1}{2}\angle B)$ and $\angle DRC = 180 - (\dfrac{1}{2}\angle D + \dfrac{1}{2}\angle C)$ . Thus,
$
\angle SPQ + \angle SRQ = \angle APB + \angle DRC \\
= 180 - (\dfrac{1}{2}\angle A + \dfrac{1}{2}\angle B) + 180 - (\dfrac{1}{2}\angle D + \dfrac{1}{2}\angle C) \\
= 360 - \dfrac{1}{2}(\angle A + \angle B + \angle C + \angle D) \\
= 360 - \dfrac{1}{2}(360) \\
= {180^0} \\
$
The sum of opposite angles of quadrilateral PQRS is ${180^0}$ . Thus PQRS is a cyclic quadrilateral.
Hence proved.
The quadrilateral formed by internal angle bisectors of a quadrilateral is cyclic.
Note: Students should always draw a diagram for better understanding of such questions. Also, they should avoid writing the angles in one letter when taking in consideration a figure where there are several other angles which might seem like the same.
Kite, Trapezoid, Parallelogram, Square, Rhombus, Rectangle comes under Quadrilateral.
A cyclic quadrilateral is given by the following figure:
A quadrilateral formed by the internal angle bisectors of a quadrilateral ABCD is PQRS:
We need to prove PQRS is cyclic.
A rule of angle equality is, vertically opposite angles are equal.
Angle sum property of a triangle gives the sum of all angles of a triangle = ${180^0}$
To prove the quadrilateral PQRS is cyclic, it is enough to prove that the sum of opposite angles of PQRS is ${180^0}$ . Implies $\angle SPQ + \angle SRQ = {180^0}$
Complete step-by-step answer:
Step 1: Consider a quadrilateral ABCD with internal bisectors AQ, BS, CS, DQ of angles $\angle A$, $\angle B$ , $\angle C$ and $\angle D$ respectively. We need to prove the quadrilateral PQRS formed by these four internal angle bisectors is cyclic.
As vertically opposite angles are equal, we obtain the following equalities:
$
\angle SPQ = \angle APB \\
\angle SRQ = \angle DRC \\
$
Adding above two formulas we get $\angle SPQ + \angle SRQ = \angle APB + \angle DRC$
As AQ is the angle bisector of $\angle A$ and P is a point on AQ, By angle sum property,
$\angle APB = 180 - (\dfrac{1}{2}\angle A + \dfrac{1}{2}\angle B)$ and $\angle DRC = 180 - (\dfrac{1}{2}\angle D + \dfrac{1}{2}\angle C)$ . Thus,
$
\angle SPQ + \angle SRQ = \angle APB + \angle DRC \\
= 180 - (\dfrac{1}{2}\angle A + \dfrac{1}{2}\angle B) + 180 - (\dfrac{1}{2}\angle D + \dfrac{1}{2}\angle C) \\
= 360 - \dfrac{1}{2}(\angle A + \angle B + \angle C + \angle D) \\
= 360 - \dfrac{1}{2}(360) \\
= {180^0} \\
$
The sum of opposite angles of quadrilateral PQRS is ${180^0}$ . Thus PQRS is a cyclic quadrilateral.
Hence proved.
The quadrilateral formed by internal angle bisectors of a quadrilateral is cyclic.
Note: Students should always draw a diagram for better understanding of such questions. Also, they should avoid writing the angles in one letter when taking in consideration a figure where there are several other angles which might seem like the same.
Kite, Trapezoid, Parallelogram, Square, Rhombus, Rectangle comes under Quadrilateral.
Recently Updated Pages
The branch of science which deals with nature and natural class 10 physics CBSE
The Equation xxx + 2 is Satisfied when x is Equal to Class 10 Maths
Define absolute refractive index of a medium
Find out what do the algal bloom and redtides sign class 10 biology CBSE
Prove that the function fleft x right xn is continuous class 12 maths CBSE
Find the values of other five trigonometric functions class 10 maths CBSE
Trending doubts
State the differences between manure and fertilize class 8 biology CBSE
Why are xylem and phloem called complex tissues aBoth class 11 biology CBSE
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
Difference Between Plant Cell and Animal Cell
What would happen if plasma membrane ruptures or breaks class 11 biology CBSE
Give 10 examples for herbs , shrubs , climbers , creepers
What precautions do you take while observing the nucleus class 11 biology CBSE
What would happen to the life of a cell if there was class 11 biology CBSE
Change the following sentences into negative and interrogative class 10 english CBSE