Example 9 - Chapter 8 Class 10 Introduction to Trignometry

Last updated at April 16, 2024 by

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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(๐Ÿ โˆ’๐’”๐’Š๐’๐Ÿ ๐‘จ) Here, A is acute (i.e. less than 90ยฐ) & cos A is positive when A is acute So, cos A = โˆš(๐Ÿ โˆ’๐’”๐’Š๐’๐Ÿ ๐‘จ) sec A sec A = 1/cosโกใ€– ๐ดใ€— sec A = ๐Ÿ/โˆš(๐Ÿ โˆ’๐’”๐’Š๐’๐Ÿ ๐‘จ) tan A We know that tan A = ๐‘ ๐‘–๐‘›โกใ€– ๐ดใ€—/๐‘๐‘œ๐‘ โกใ€– ๐ดใ€— Putting value of cos A tan A = ๐’”๐’Š๐’โกใ€– ๐‘จใ€—/โˆš(๐Ÿ โˆ’ ๐’”๐’Š๐’๐Ÿ ๐‘จ)

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