Example 1 : <\/span>\\(sin5x + sin2x – sinx\\over {cos5x + 2cos3x + 2cos^x + cosx}\\) is equal to –<\/p>\n Solution : <\/span>L.H.S. = \\(2sin2xcos3x + sin2x\\over{2cos3x.cos2x + 2cos3x + 2cos^2x}\\) Example 2 : <\/span> Prove that : \\(2cos2A+1\\over {2cos2A-1}\\) = tan(\\(60^{\\circ}\\) + A)tan(\\(60^{\\circ}\\) – A)<\/p>\n Solution : <\/span>R.H.S. = tan(\\(60^{\\circ}\\) + A)tan(\\(60^{\\circ}\\) – A) Example 3 : <\/span>If A + B + C = \\(3\\pi\\over 2\\), then cos2A + cos2B + cos2C is equal to-<\/p>\n Solution : <\/span>cos2A + cos2B + cos2C = 2cos(A+B)cos(A-B)+cos2C Practice these given trigonometry examples to test your knowledge on concepts of trigonometry.<\/p>\n \n <\/div>\n <\/div>\n","protected":false},"excerpt":{"rendered":" Here you will learn some trigonometry examples for better understanding of trigonometry concepts. Example 1 : \\(sin5x + sin2x – sinx\\over {cos5x + 2cos3x + 2cos^x + cosx}\\) is equal to – Solution : L.H.S. = \\(2sin2xcos3x + sin2x\\over{2cos3x.cos2x + 2cos3x + 2cos^2x}\\) = \\(sin2x[2cos3x+1]\\over {2[cos3x(cos2x+1)+(cos^2x)]}\\) = \\(sin2x[2cos3x+1]\\over {2[cos3x(2cos^2x)+(cos^2x)]}\\) = \\(sin2x[2cos3x+1]\\over {2cos^2x(2cos3x+1)}\\) = tanx Example …<\/p>\n
\n = \\(sin2x[2cos3x+1]\\over {2[cos3x(cos2x+1)+(cos^2x)]}\\)
\n = \\(sin2x[2cos3x+1]\\over {2[cos3x(2cos^2x)+(cos^2x)]}\\)
\n = \\(sin2x[2cos3x+1]\\over {2cos^2x(2cos3x+1)}\\) = tanx<\/p>\n
\n\n \n
\n = (\\(tan60^{\\circ}+tanA\\over {1-tan60^{\\circ}tanA}\\))(\\(tan60^{\\circ}-tanA\\over {1+tan60^{\\circ}tanA}\\))
\n = (\\(\\sqrt{3}+tanA\\over {1-\\sqrt{3}tanA}\\))(\\(\\sqrt{3}-tanA\\over {1+\\sqrt{3}tanA}\\))
\n = \\(3-tan^2A\\over{1-3tan^2A}\\) = \\(3cos^2A-sin^2A\\over {cos^2A-3sin^2A}\\) = \\(2cos^2A+cos^2A-2sin^2A+sin^2A\\over {2cos^2A-2sin^2A-sin^2A-cos^2A}\\)
\n = \\(2(cos^2A-sin^2A)+cos^2A+sin^2A\\over {2(cos^2A-sin^2A)-(sin^2A+cos^2A)}\\)
\n = \\(2cos2A+1\\over {2cos2A-1}\\) = R.H.S<\/p>\n
\n\n \n
\n = 2cos(\\(3\\pi\\over 2\\) – C)cos(A-B) + cos2C \\(\\because\\) A + B + C = \\(3\\pi\\over 2\\)
\n = -2sinC cos(A-B) + 1 – 2\\(sin^2C\\) = 1 – 2sinC[cos(A-B)+sinC]
\n = 1 – 2sinC[cos(A-B) + sin(\\(3\\pi\\over 2\\)-(A+B))]
\n = 1 – 2sinC[cos(A-B)-cos(A+B)]
\n = 1 – 4sinA sinB sinC\n <\/p>\n
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