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Prove that the rectangle circumscribing a circle is a square.

 

Note : This is similar to Ex 10.2, 11 of NCERT – Chapter 10 Class 10

Check the answer here https://www.teachoo.com/1837/539/Ex-10.2--11---Prove-that-parallelogram-circumscribing-a-circle/category/Ex-10.2/


Transcript

Question 22 Prove that the rectangle circumscribing a circle is a square. Given: A circle with centre O. A rectangle ABCD touching the circle at points P, Q, R and S To prove: ABCD is a square Proof: A rectangle is a square with all sides equal, So, we have to prove all sides equal We know that lengths of tangents drawn from external point are equal Hence, AP = AS BP = BQ CR = CQ DR = DS Adding (1) + (2) + (3) + (4) AP + BP + CR + DR = AS + BQ + CQ + DS (AP + BP) + (CR + DR) = (AS + DS) + (BQ + CQ) AB + CD = AD + BC …(1) …(2) …(3) …(4) Since ABCD is a rectangle, Opposite sides are equal ∴ CD = AB & BC = AD AB + AB = AD + AD 2AB = 2AD AB = AD So, AB = AD & AB = CD & AD = BC So, AB = CD = AD = CD So, ABCD is a rectangle with all sides equal ∴ ABCD is a square Hence proved

  1. Class 10
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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo