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


Ex 8.1, 3 If sin A = 3/4 , calculate cos A and tan A. Given sin A = 3/4 (𝑠𝑖𝑑𝑒 π‘œπ‘π‘π‘œπ‘ π‘–π‘‘π‘’ π‘‘π‘œ ∠𝐴)/π»π‘¦π‘π‘œπ‘‘π‘’π‘›π‘’π‘ π‘’ = 3/4 𝑩π‘ͺ/𝑨π‘ͺ = πŸ‘/πŸ’ 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 = √7π‘₯2 AB = βˆšπŸ• x Now, we need to find cos A & tan A cos A = (𝑠𝑖𝑑𝑒 π‘Žπ‘‘π‘—π‘Žπ‘π‘’π‘›π‘‘ π‘‘π‘œ ∠ 𝐴)/π»π‘¦π‘π‘œπ‘‘π‘’π‘›π‘’π‘ π‘’ = 𝐴𝐡/𝐴𝐢 = (βˆšπŸ• 𝒙)/πŸ’π’™ = βˆšπŸ•/πŸ’ tan A = (𝑠𝑖𝑑𝑒 π‘œπ‘π‘π‘œπ‘ π‘–π‘‘π‘’ π‘‘π‘œ ∠𝐴)/(𝑠𝑖𝑑𝑒 π‘Žπ‘‘π‘—π‘Žπ‘π‘’π‘›π‘‘ π‘‘π‘œβˆ π΄) = 𝐡𝐢/𝐴𝐡 = πŸ‘π’™/(βˆšπŸ• 𝒙) = πŸ‘/βˆšπŸ•

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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.