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


Transcript

Ex 8.1, 4 Given 15 cot A = 8, find sin A and sec A. Given 15 cot A = 8 cot A = ๐Ÿ–/๐Ÿ๐Ÿ“ Now, tan A = 1/cotโก๐ด = 1/(8/15) = ๐Ÿ๐Ÿ“/๐Ÿ– Now, tan A = 15/8 (๐‘ ๐‘–๐‘‘๐‘’ ๐‘œ๐‘๐‘๐‘œ๐‘ ๐‘–๐‘ก๐‘’ ๐‘ก๐‘œ โˆ ๐ด)/(๐‘ ๐‘–๐‘‘๐‘’ ๐‘Ž๐‘‘๐‘—๐‘Ž๐‘๐‘’๐‘›๐‘ก ๐‘ก๐‘œโˆ ๐ด) = 15/8 ๐‘ฉ๐‘ช/๐‘จ๐‘ฉ=๐Ÿ๐Ÿ“/๐Ÿ– Let BC = 15x & AB = 8x Finding AC Using Pythagoras theorem, (Hypotenuse)2 = (Height)2 + (Base)2 AC2 = AB2 + BC2 AC2 = (8x)2 + (15x)2 AC2 = 64 x2 + 225 x2 AC2 = 289 x2 AC2 = (17x)2 AC = 17x Now, we need to find sin A & sec A sin A = (๐‘ ๐‘–๐‘‘๐‘’ ๐‘œ๐‘๐‘๐‘œ๐‘ ๐‘–๐‘ก๐‘’ ๐‘ก๐‘œ โˆ ๐ด)/๐ป๐‘ฆ๐‘๐‘œ๐‘ก๐‘’๐‘›๐‘ข๐‘ ๐‘’ = ๐ต๐ถ/๐ด๐ถ = 15๐‘ฅ/17๐‘ฅ = ๐Ÿ๐Ÿ“/๐Ÿ๐Ÿ• For sec A , Finding cos A first cos A = (๐‘ ๐‘–๐‘‘๐‘’ ๐‘Ž๐‘‘๐‘—๐‘Ž๐‘๐‘’๐‘›๐‘ก ๐‘ก๐‘œ โˆ ๐ด)/๐ป๐‘ฆ๐‘๐‘œ๐‘ก๐‘’๐‘›๐‘ข๐‘ ๐‘’ = ๐ด๐ต/๐ด๐ถ = 8๐‘ฅ/17๐‘ฅ = ๐Ÿ–/๐Ÿ๐Ÿ• And, sec A = 1/cosโกใ€– ๐ดใ€— = 1/(8/17) = ๐Ÿ๐Ÿ•/๐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.