Question:

Evalutating the integral?

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evalute the integral

intergrate from0 to pie/3 (sinx+ sinx tan2x)/ sec2x

trig is not my strong point can someone help he with this

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  1. Buri is corrct if it is (tanx)^2 and (secx)^2

    If it is tan2x and sec2x, it will be different.

    In that case

    (sinx+ sinx tan2x)/ sec2x

    (sinx+ sinx tan2x)cos2x

    =sinx cos2x + sinxsin2x

    =(1/2){ sin3x - sinx} +(1/2) {cosx - cos3x} and then integrate

    Integral = (1/2){- (c0s3x)/3 +cosx} + (1/2){ sinx -(sin3x)/3}

    and evaluate between the given limits.


  2. ∫ (sin(x) + sin(x)tan²(x))/sec²(x) dx

    factor out sin(x)

    =∫ [sin(x) ][1 + tan² (x)]/sec²(x) dx

    recall that sec²(x) = 1 + tan²(x)

    thus,

    =∫ [sin(x) ][sec²(x)]/sec²(x) dx

    =∫ sin(x) dx = -cos(x) with limits from 0 to pi/3

    =[-cos(pi/3)] - [-cos(0)]

    =[-(1/2)+ 1]

    =1/2

    =)

  3. Simplify the function your integrating:

    [sin(x) + sin(x)tan²(x)]/sec²(x)

    = [sin(x)(tan²(x) + 1)]/sec²(x); after factoring out the sin(x)

    = [sin(x)sec²(x)]/sec²(x); because of the identity tan²(x) + 1 = sec²(x)

    = sin(x)

    Therefore,

    ∫ (sin(x) + sin(x)tan²(x))/sec²(x) dx = ∫ sin(x) dx = -cos(x)

    Now evaluating at the bounds:

    ∫ [0, π/3] sin(x) dx = [0, π/3] -cos(x) = -cos(π/3) - (-cos(0)) = -(1/2) + 1 = 1/2

    Hope this helps!

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