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Mathematics 8 Online
zarkam21:

Last 2

zarkam21:

1 attachment
Vocaloid:

|dw:1527827868649:dw| just the first line

zarkam21:

would the 4 apply to the cos or isin?

Vocaloid:

|dw:1527828022755:dw|

Vocaloid:

4 is the r value, it has nothing to do with the cos and sin values

zarkam21:

okay so do I cube the entire equation?

Vocaloid:

you are given [r(cos(theta) + isin(theta)]^n identify your r, theta, and n values, then write your solution in the form r^n * (cos(n*theta) + i sin(n*theta))

zarkam21:

cos(7pi/9)+isin(7pi/9)^3

Vocaloid:

now identify what your r, n, and theta are

zarkam21:

r=4 n=3 theta=7pi/9

Vocaloid:

good, so r^n * (cos(n*theta) + i sin(n*theta)) = ?

zarkam21:

r^n * (cos(n*theta) + i sin(n*theta)) 4^3*(cos(3*7pi/9)+isin(3*7pi/9))

Vocaloid:

good it wants the solution in standard form so you just need to distribute the 4^3 and use your calculator to evaluate the costheta and sintheta values to get something in the form a + bi

zarkam21:

64(1/2+(i)sqrt3/2)

Vocaloid:

good but distribute that 64

zarkam21:

32+32isqrt3

Vocaloid:

good but as a minor change it wants the solution in a +bi form so 32 + 32sqrt(3)i

Vocaloid:

then go through the same steps for 17

zarkam21:

okay same thing ofr the next

zarkam21:

okay will be back in a few

zarkam21:

cos(72)+isin(72)^5 r=1/2 n=5 theta=72 r^n * (cos(n*theta) + i sin(n*theta)) = 1/2^5*(cos(5*72)+isin(5*72)) 1/32

Vocaloid:

good now convert to a + bi form

zarkam21:

1+32i?

Vocaloid:

what are cos(5*72) and sin(5*72) = ?

zarkam21:

1 and 0

Vocaloid:

good so putting it together gives us 1/32 + 0i

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