The side QR of triangle pqr is produced to a point s if the bisector of angle special and angle PRS meet at point t qpr and then prove that angle QtR in is equal to 1/2 by angle qpr
Answers
Answer:
Given:
In ΔPQR,
QR is produced to S
The bisectors of ∠PQR & ∠PRS meet at a point T
To prove:
∠QTR = \frac{1}{2}
2
1
∠QPR
Solution:
Concept to be used: The exterior angle of a triangle is equal to the sum of two interior opposite angles of the triangle
Considering the exterior angle of ΔTQR, we have
∠TRS = ∠TQR + ∠QTR
⇒ ∠QTR = ∠TRS - ∠TQR ....... (i)
Considering the exterior angle of Δ PQR, we have
∠PRS = ∠PQR + ∠QPR
[∵ QT is the bisector of ∠PQR & TR is the bisector of ∠PRS (as shown in the fig)]
⇒ 2∠TRS = 2∠TQR + ∠QPR
⇒ ∠QPR = 2∠TRS - 2∠TQR
⇒ ∠QPR = 2[∠TRS - ∠TQR]
⇒ ∠TRS - ∠TQR = \frac{1}{2}
2
1
∠QPR ....... (ii)
Now, on comparing (i) & (ii), we get
\boxed{\boxed{\underline{\bold{\angle QTR = \frac{1}{2}\angle QPR }}}}
∠QTR=
2
1
∠QPR
Hence proved