Question

if x= 138degrees 36 minutes and 221degrees 24 minutes solve, cos(2x)-sin^2(x/2)+3/4. Been at this for an hour how can express the answer as a fraction?

Answer 1

Note that 138degrees 36mins and 221 degrees 24mins = x = -(3/4)

Answer 2

im having hard time interpreting the question :o

Answer 3

if psble, could u please take snapshot of original question and attach the pic ? :)

Answer 4

\[\cos(2x)-\sin^2(\frac{ x }{ 2 })+(\frac{ 3 }{ 4 })\]

Answer 5

\[x=-(\frac{ 3 }{ 4 })\]

Answer 6

\[
\sin^2\left(\frac x2\right) = \frac{1-\cos(x)}{2}
\]

Answer 7

I still don't know what the point of the question is through.

Answer 8

I'm just trying to check my work

Answer 9

wish i could check ur work.. .but im not able to get wat the question is asking us to solve/find :|

Answer 10

I'll rephrase it

Answer 11

\[x=-(\frac{ 3 }{ 4 })\] \[\cos(2x)-\sin^2(\frac{ x }{ 2 })+(\frac{ 3 }{ 4 }) = y\] solve for y

Answer 12

John the question starts
if x= 138degrees 36 minutes and (then something seems missing here)

221degrees 24 minutes

Answer 13

I meant that x is equal to both 138degrees 36mines and 221degrees 24minutes, but I realized that it's easier if I expressed both of them as -(3/4)

Answer 14

cos(-(3/4)))

Answer 15

\(\cos^{-1}(-3/4) = 138^o 36'\)

Answer 16

got you :)

Answer 17

I'm trying to substitute all the X into (-3/4)

Answer 18

\(\cos(2x)-\sin^2(\frac{ x }{ 2 })+(\frac{ 3 }{ 4 }) = y \)

basically the question is to evaluate y at \(x = \cos^{-1}(-3/4)\)

Answer 19

step1 : convert all terms into cos(x)

Answer 20

use below identites :

\(\cos(2x) = 2\cos^2x-1\)

\(\sin^2(\frac{x}{2}) = \frac{1-\cos x}{2}\)

Answer 21

once u have expressed it in terms of cos(x),
u can replace cos(x) wid -3/4

Answer 22

following that I get, (-(3/4))-(7/8)+(3/4)

Answer 23

okie lemme check.. .

Answer 24

Thanks I got it

Answer 25

hmm im getting 0

Answer 26

\(\large \cos(2x)-\sin^2(\frac{ x }{ 2 })+(\frac{ 3 }{ 4 }) = y\)

\(\large 2\cos^2x - 1 -\frac{1-\cos x}{2}+(\frac{ 3 }{ 4 }) = y\)

\(\large 2(\frac{-3}{4})^2 - 1 -\frac{1-\frac{-3}{4}}{2}+(\frac{ 3 }{ 4 }) = y\)

\(\large \frac{9}{8} - 1 -\frac{7}{8}+(\frac{ 3 }{ 4 }) = y\)

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