Check sibling questions

7.8.jpg


Theorem 7.8 - Chapter 7 Class 9 Triangles - Part 2

Get live Maths 1-on-1 Classs - Class 6 to 12


Transcript

Theorem 7.8 :- The sum of any two sides of a triangle is greater than the third side. Given :- A triangle ABC To Prove :- AB + AC > BC . Construction:- Extend AB to D such that AD = AC Proof:- In Δ ACD AD = AC ∴ ∠1 = ∠2 Now, ∠BCD = ∠BCA + ∠1 = ∠BCA + ∠2 > ∠2 Now, in ∆BCD ∠BCD > ∠2 ⇒ BD > BC ⇒ AB + AD > BC ⇒ AB + AC > BC Similarly we can prove AB + BC > AC & AC + BC > AB Hence Proved

Ask a doubt
Davneet Singh's photo - Co-founder, Teachoo

Made by

Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.