Slide22.JPG

Slide23.JPG
Slide24.JPG  

Learn in your speed, with individual attention - Teachoo Maths 1-on-1 Class


Transcript

Ex 3.1, 6 If in two circles, arcs of the same length subtend angles 60° and 75° at the centre, find the ratio of their radii. We know that 𝑙 = r θ Let the radius of the two circles be r1 and r2 Length of arc of 1st Circle 𝑙 = r1 θ = r1 × 60° Converting into radians = r1 × 60° × 𝜋/(180°) = r1 × 𝝅/𝟑 Length of arc of 2nd circle 𝑙 = r2 θ = r2 × 75° Converting into radians = r2 × 75° × 𝜋/(180°) = r2 × 𝟓𝝅/𝟏𝟐 Given that Length of 1st arc = length of 2nd arc r1 × 𝝅/𝟑 = r2 × 𝟓𝝅/𝟏𝟐 𝑟1/𝑟2 = 5𝜋/12 × 3/𝜋 𝒓𝟏/𝒓𝟐 = 𝟓/𝟒 Hence, r1 : r2 = 22 : 13 So, Ratio of Radius = 5 : 4

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.