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Example 9 - Chapter 8 Class 10 Introduction to Trignometry

Last updated at May 29, 2023 by

Example 12 - Express cos A, tan A and sec A in terms of sin A - Expressing ratios in other ratios

Example 12 - Chapter 8 Class 10 Introduction to Trignometry - Part 2

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Example 9 Express the ratios cos A, tan A and sec A in terms of sin A. cos A Since, cos2 A + sin2 A = 1 cos2 A = 1 โ€“ sin2 A cos A = ยฑโˆš(1 โˆ’๐‘ ๐‘–๐‘›2 ๐ด) Here, A is acute (i.e. less than 90ยฐ) & cos A is positive when A is acute So, cos A = โˆš(1 โˆ’๐‘ ๐‘–๐‘›2 ๐ด) sec A sec A = ๐Ÿ/๐œ๐จ๐ฌโกใ€– ๐‘จใ€— sec A = 1/โˆš(1 โˆ’๐‘ ๐‘–๐‘›2 ๐ด) tan A We know that tan A = ๐’”๐’Š๐’โกใ€– ๐‘จใ€—/๐’„๐’๐’”โกใ€– ๐‘จใ€— Putting value of cos A tan A = sinโกใ€– ๐ดใ€—/โˆš(1 โˆ’ ๐‘ ๐‘–๐‘›2 ๐ด)

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