Question

sin x = 3/5 , π/2 < x < π A.cos(x/2) B. sin(x/2) C. Tan(x/2)

Answer 1

what do we have to find out?

Answer 2

A. Cos (x/2)
B. Sin (x/2)
C. Tan (x/2)

Answer 3

so do you know how to find x? in sin x = 3/5

Answer 4

@jewest19

Answer 5

someone can take over. not wasting mi time waiting when i have a geology exam to revise for

Answer 6

if i knew i wouldnt post it. Dont worry about wasting your time, I was trying to help someone else.

Answer 7

use "half angle" formula to find \(\cos(\frac{x}{2})\)

Answer 8

i.e. use
\[\cos(\frac{x}{2})=\sqrt{\frac{1+\cos(x)}{2}}\]

Answer 9

in this case the answer is positive, and also in this case you can see from the triangle that \(\cos(x)=\frac{4}{5}\)

Answer 10

4/5 is incorrect, thats what i thought it was

Answer 11

it is not \(\frac{4}{5}\)

Answer 12

\(\cos(x)=\frac{4}{5}\) you are looking for \(\cos(\frac{x}{2})\)

Answer 13

yeah

Answer 14

replace \(\cos(x)\) in the "half angle" formula i wrote above by \(\frac{4}{5}\) to find the answer

Answer 15

put \(\cos(x)=\frac{4}{5}\) here :
\[\cos(\frac{x}{2})=\sqrt{\frac{1+\cos(x)}{2}}\]

Answer 16

ok im working it

Answer 17

\[\frac{3\sqrt{2}}{ \sqrt{5} }\]

Answer 18

@satellite73 idk! i got it wrong again

Answer 19

\[\cos(\frac{x}{2}) = \sqrt{\frac{1+\cos(x)}{2}} = \sqrt{\frac{1+\frac{4}{5}}{2}} = \sqrt{\frac{\frac{5}{5}+\frac{4}{5}}{2}} =\sqrt{\frac{\frac{9}{5}}{2}}=\sqrt{\frac{9}{10}} = \]\[\frac{\sqrt{9}}{\sqrt{10}} = \frac{3}{\sqrt{10}} = \frac{3\sqrt{10}}{10}\]