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    If sin A=817\frac{8 }{17}178​​ then what is the value of cot A + sec A?
    Question

    If sin A=817\frac{8 }{17}​ then what is the value of cot A + sec A?

    A.

    211202\frac{1}{120}​​
    ​​

    B.

    31120\frac1{120 }​​

    C.

    41120\frac1{120 }​​

    D.

    51120\frac1{120 }​​

    Correct option is B

    Given:
    sin A =817 \frac{8}{17}​​
    Formula Used:
    cotA=cosAsinA secA=1cosAcotA = \frac{\cos A}{\sin A}\\\ \\secA = \frac{1}{\cos A}​​
    sin2A+cos2A=1\sin^2 A + \cos^2 A = 1​​
    Solution:
    cosA=1sin2A=1(817)2cosA=164289=225289=1517.\cos A = \sqrt{1 - \sin^2 A} = \sqrt{1 - \left(\frac{8}{17}\right)^2}\\\cos A = \sqrt{1 - \frac{64}{289}} = \sqrt{\frac{225}{289}} = \frac{15}{17}.​​

    cotA=cosAsinA=1517817=158.\cot A = \frac{\cos A}{\sin A} = \frac{\frac{15}{17}}{\frac{8}{17}} = \frac{15}{8}.​​
    secA=1cosA=1715.\sec A = \frac{1}{\cos A} = \frac{17}{15}.​​
    cotA+secA=158+1715=225+136120=361120=31120\cot A + \sec A = \frac{15}{8} + \frac{17}{15} = \frac{225 + 136}{120} = \frac{361}{120}= 3 \frac1{120}​​
    Alternate Method:
    Sin A = 817=PH\frac{ 8}{17} = \frac PH​​

    As we know, 8, 15, 17 are Pythagorean triplet, then Base = 15,

    Cot A + Sec A

    => BP+HB\frac BP + \frac HB​​

    158+1715=225+136120=361120=31120\rightarrow \frac{15}{8} + \frac{17}{15} = \frac{225 + 136}{120} = \frac{361}{120}= 3 \frac1{120}​​

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