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


Transcript

Ex 8.1, 3 If sin A = 3/4 , calculate cos A and tan A. Given sin A = 3/4 (𝑠𝑖𝑑𝑒 𝑜𝑝𝑝𝑜𝑠𝑖𝑡𝑒 𝑡𝑜 ∠𝐴)/𝐻𝑦𝑝𝑜𝑡𝑒𝑛𝑢𝑠𝑒 = 3/4 𝑩𝑪/𝑨𝑪 = 𝟑/𝟒 Let BC = 3x AC = 4x We find AB using Pythagoras Theorem In right triangle ABC Using Pythagoras theorem Hypotenuse2 = Height2 + Base2 AC2 = AB2 + BC2 (4x)2 = AB2 + (3x)2 16x2 = AB2 + 9x2 16x2 – 9x2 = AB2 7x2 = AB2 AB2 = 7x2 AB = √7𝑥2 AB = √𝟕 x Now, we need to find cos A & tan A cos A = (𝑠𝑖𝑑𝑒 𝑎𝑑𝑗𝑎𝑐𝑒𝑛𝑡 𝑡𝑜 ∠ 𝐴)/𝐻𝑦𝑝𝑜𝑡𝑒𝑛𝑢𝑠𝑒 = 𝐴𝐵/𝐴𝐶 = (√𝟕 𝒙)/𝟒𝒙 = √𝟕/𝟒 tan A = (𝑠𝑖𝑑𝑒 𝑜𝑝𝑝𝑜𝑠𝑖𝑡𝑒 𝑡𝑜 ∠𝐴)/(𝑠𝑖𝑑𝑒 𝑎𝑑𝑗𝑎𝑐𝑒𝑛𝑡 𝑡𝑜∠𝐴) = 𝐵𝐶/𝐴𝐵 = 𝟑𝒙/(√𝟕 𝒙) = 𝟑/√𝟕

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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 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.