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Mathematics 14 Online
OpenStudy (anonymous):

Not sure how they got those x's

OpenStudy (anonymous):

OpenStudy (anonymous):

you're substituting the x's in.

OpenStudy (anonymous):

oh, in the original equation ?

OpenStudy (anonymous):

so, 2sinx+sin^2x ...2sin(o)+sin^2(0) ? :S

OpenStudy (anonymous):

Sorry could you please show me Im not very good at trig

OpenStudy (anonymous):

You just posted it! Yes lol...

OpenStudy (anonymous):

Okayyy so then 0+sin^2 (0) = 0 ?

OpenStudy (anonymous):

2sin(-1) + sin^2 (-1) = I got decimals

OpenStudy (anonymous):

You got decimals? Then you're fine.

OpenStudy (anonymous):

but I dont know how they got x= pi / 2 + 2n pi and 3pi/2 + 2npi

OpenStudy (freckles):

how is ling defined?

OpenStudy (freckles):

oh tangent line=ling?

OpenStudy (freckles):

\[\cos(x)=0 \text{ when } x=\pi/2 \text{ or } x=3 \pi/2 \text{ right? } \]

OpenStudy (freckles):

This is according to the unit circle

OpenStudy (freckles):

now +2npi just means the number of rotations we went around a circle

OpenStudy (anonymous):

ohhhhhhhhhh okay okay ! so then to find by y value. I would pi/2 and 3pi/ 2? so 2sin(pi/2)+sin^(pi/2) and 2sin(3pi/2)+sin^2(3pi/2) ?

OpenStudy (freckles):

\[f(\frac{\pi}{2}+2 n \pi )=2 \sin(\frac{\pi}{2}+2 n \pi )+[\sin(\frac{\pi}{2}+2 n \pi )]^2 \\ = 2[\sin(\frac{\pi}{2})\cos(2\pi n)+\cos(\frac{\pi}{2})\sin(2 \pi n)] \\+[(\sin(\frac{\pi}{2})\cos(2\pi n ) +\cos(\frac{\pi}{2})\sin(2 \pi n)]^2 \\ =2[1 \cdot \cos(2 \pi n) + 0 \cdot 0 ]+[1 \cdot \cos(2 \pi n)+0 \cdot 0 ]^2 \] \[=2 \cos(2 \pi n )+(\cos(2 \pi n ))^2 \] so cos(2pi)=1 so cos(2pi*n)=1

OpenStudy (freckles):

and yeah you could have just plugged in pi/2 but i wanted to by fancy

OpenStudy (freckles):

and also plug in 3pi/2 also

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