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    hey i got few questions to test ur knowledge. show all the steps. i cant do them u no. i have the answers. ill type them for and tell the person, who gets them right.


    1. find values of x 0,360

    7 cos x + sin x = 5
    :rolleyes:
    2. (a) solve sin2x = cos ^ 2 x, 0> x >360
    (b) solve cos 2x = 2 sin ^2 x
    :cool:
    3. find the smallest positive value of x for which
    7 cos x - 4 sin x
    takes its maximum value

    4. expand (x + y) ^ 6 and find (4.01)^6

    5. find the values of x for which
    sin x + sin 3 x + sin 5 x = 0
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    dey r hard. wot if dey come in exam :confused:
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    working on them now
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    (Original post by f_malik)
    hey i got few questions to test ur knowledge. show all the steps. i cant do them u no. i have the answers. ill type them for and tell the person, who gets them right.


    1. find values of x 0,360

    7 cos x + sin x = 5
    Can do question 1

    7 cos x + sin x = 5
    7 cos x = 5 - sin x
    (7 cos x)^2 = (5 - sin x)^2
    49 cos^2 x = sin^2 x - 10 sin x +25
    49(1 - sin^2 x) = sin^2 x - 10 sin x +25
    49 - 49sin^2 x = sin^2 x - 10 sin x +25
    50 sin^2 x - 10 sin x -24 = 0

    use quadratic formula

    sin x = 0.8 or -0.6

    x = sin^-1 0.8 = 53.13 (there wil be other values too)

    Is this right?
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    (Original post by f_malik)
    (a) solve sin2x = cos ^ 2 x, 0> x >360
    sin2x = cos^2 x
    2sinxcosx = cos^x
    2sinx = cos^x / cos x
    2sinx = cos x
    sinx / cos x = 1/2
    tan x = 1/2
    x = 26.6
    and x = 180 + 26.6 = 206.6

    should be correct... wil do the rest after the match
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    Use Rsin(A+B) ..
 
 
 

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