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Mathematics 11 Online
zarkam21:

A?

zarkam21:

1 attachment
Vocaloid:

this calculation is taking me a while

zarkam21:

I'm sorry i dont want you to have to do long calculations for me

zarkam21:

>.<

Vocaloid:

so what I have so far is that you would multiply the num and denom csc(4x) - cot(4x), that'll convert the denominator into csc^2(4x) - cot^2(4x) which is 1 I believe

zarkam21:

oh okay got what you are doing

Vocaloid:

I don't really like doing this but I can't think of a way to solve this w/o plugging in x values

iGreen:

Well, you could express them all in cos & sin terms and then simplify from there.

iGreen:

Like this: \(\sf\dfrac{\frac{1}{sin(4x)}-\frac{cos(4x)}{sin(4x)}}{\frac{1}{sin(4x)}+\frac{cos(4x)}{sin(4x)}}\)

iGreen:

Combine the fractions in both the numerator and denominator: \(\sf\dfrac{\frac{1-cos(4x)}{sin(4x)}}{\frac{1+cos(4x)}{sin(4x)}}\)

iGreen:

Use the division rule: \(\sf\dfrac{(1-cos(4x))sin(4x)}{sin(4x)(1+cos(4x))}\)

iGreen:

Cancel out sin(4x): \(\sf\dfrac{(1-cos(4x))\cancel{sin(4x)}}{\cancel{sin(4x)}(1+cos(4x))}\) \(\sf\dfrac{1-cos(4x)}{1+cos(4x)}\)

zarkam21:

and get b ?

iGreen:

Not quite, try again.

zarkam21:

D

zarkam21:

because of the 4x

iGreen:

We could do: \(\sf\dfrac{1-cos(2\cdot 2x)}{1+cos(2\cdot 2x)}\)

zarkam21:

C :/

iGreen:

Ohhh, then we could multiply 1/2 to the numerator and denominator, then use the identities: \(\sf sin^2(x)=0.5(1-cos(2x))\) \(\sf cos^2(x)=0.5(1+cos(2x))\)

iGreen:

Which leaves us with: \(\sf\dfrac{sin^2(2x)}{cos^2(2x)}\) \(\sf tan^2(2x)\) \(\Huge\checkmark\)

zarkam21:

thank you so much I really do appreciate it

iGreen:

No problem.

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