Class 9 Exam  >  Class 9 Questions  >  the sides ab and ac of a triangle ABC are pro... Start Learning for Free
the sides ab and ac of a triangle ABC are produced to P and Q respectively. if the bisector of angle abc and angle ACB intersected at then prove that is equal to angle BOC is equal to 90 minus half angle A
?
Most Upvoted Answer
the sides ab and ac of a triangle ABC are produced to P and Q respecti...
**Given:**
- Triangle ABC with sides AB and AC produced to points P and Q respectively.
- The bisector of angle ABC and angle ACB intersect at point O.

**To prove:**
- Angle AOB = Angle BOC = 90 - (1/2) * Angle A

**Proof:**

**1. Construction:**
- Join OP and OQ.

**2. Statement:**
- Angle BOP = Angle COQ (Vertically opposite angles)
- Angle AOB = Angle COQ + Angle COB (Angle addition property)

**3. Proof:**
- Since OP is the bisector of angle ABC, it divides angle ABC into two equal angles, i.e., Angle BOP = Angle POC.
- Similarly, since OQ is the bisector of angle ACB, it divides angle ACB into two equal angles, i.e., Angle COQ = Angle QOB.
- Therefore, Angle BOP = Angle POC = Angle COQ = Angle QOB.
- By vertically opposite angles, Angle BOP = Angle COQ.
- Using the angle addition property, Angle AOB = Angle COQ + Angle COB.
- Substitute Angle BOP = Angle COQ, Angle POC = Angle BOC, and Angle QOB = Angle BOC to get Angle AOB = Angle COQ + Angle COB = Angle BOP + Angle BOC.
- Therefore, Angle AOB = Angle BOP + Angle BOC.
- Since Angle BOP = Angle BOC, we can rewrite the equation as Angle AOB = Angle BOC + Angle BOC = 2 * Angle BOC.
- Rearrange the equation to get Angle BOC = (1/2) * Angle AOB.
- Since Angle AOB = 180 - Angle A (sum of angles in a triangle), we substitute it in the equation to get Angle BOC = (1/2) * (180 - Angle A).
- Simplify to get Angle BOC = 90 - (1/2) * Angle A.
- Therefore, Angle BOC = 90 - (1/2) * Angle A.

Hence, proved.
Community Answer
the sides ab and ac of a triangle ABC are produced to P and Q respecti...
a+b+c=180
b+c=180-a      ...(1)
obc=1/2abc
ocb=1/2acb
obc+ocb=1/2(abc+acb)
using (1)     
obc+ocb=90-1/2a   ...(2)
but, boc=180-(obc+ocb)
so using (2)     boc=180-(90-1/2a)
==>boc= 90+12/a

Attention Class 9 Students!
To make sure you are not studying endlessly, EduRev has designed Class 9 study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in Class 9.
Explore Courses for Class 9 exam

Top Courses for Class 9

the sides ab and ac of a triangle ABC are produced to P and Q respectively. if the bisector of angle abc and angle ACB intersected at then prove that is equal to angle BOC is equal to 90 minus half angle A Related: Hots Questions- Triangles?
Question Description
the sides ab and ac of a triangle ABC are produced to P and Q respectively. if the bisector of angle abc and angle ACB intersected at then prove that is equal to angle BOC is equal to 90 minus half angle A Related: Hots Questions- Triangles? for Class 9 2024 is part of Class 9 preparation. The Question and answers have been prepared according to the Class 9 exam syllabus. Information about the sides ab and ac of a triangle ABC are produced to P and Q respectively. if the bisector of angle abc and angle ACB intersected at then prove that is equal to angle BOC is equal to 90 minus half angle A Related: Hots Questions- Triangles? covers all topics & solutions for Class 9 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for the sides ab and ac of a triangle ABC are produced to P and Q respectively. if the bisector of angle abc and angle ACB intersected at then prove that is equal to angle BOC is equal to 90 minus half angle A Related: Hots Questions- Triangles?.
Solutions for the sides ab and ac of a triangle ABC are produced to P and Q respectively. if the bisector of angle abc and angle ACB intersected at then prove that is equal to angle BOC is equal to 90 minus half angle A Related: Hots Questions- Triangles? in English & in Hindi are available as part of our courses for Class 9. Download more important topics, notes, lectures and mock test series for Class 9 Exam by signing up for free.
Here you can find the meaning of the sides ab and ac of a triangle ABC are produced to P and Q respectively. if the bisector of angle abc and angle ACB intersected at then prove that is equal to angle BOC is equal to 90 minus half angle A Related: Hots Questions- Triangles? defined & explained in the simplest way possible. Besides giving the explanation of the sides ab and ac of a triangle ABC are produced to P and Q respectively. if the bisector of angle abc and angle ACB intersected at then prove that is equal to angle BOC is equal to 90 minus half angle A Related: Hots Questions- Triangles?, a detailed solution for the sides ab and ac of a triangle ABC are produced to P and Q respectively. if the bisector of angle abc and angle ACB intersected at then prove that is equal to angle BOC is equal to 90 minus half angle A Related: Hots Questions- Triangles? has been provided alongside types of the sides ab and ac of a triangle ABC are produced to P and Q respectively. if the bisector of angle abc and angle ACB intersected at then prove that is equal to angle BOC is equal to 90 minus half angle A Related: Hots Questions- Triangles? theory, EduRev gives you an ample number of questions to practice the sides ab and ac of a triangle ABC are produced to P and Q respectively. if the bisector of angle abc and angle ACB intersected at then prove that is equal to angle BOC is equal to 90 minus half angle A Related: Hots Questions- Triangles? tests, examples and also practice Class 9 tests.
Explore Courses for Class 9 exam

Top Courses for Class 9

Explore Courses
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev