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Trigonometry 8 Online
OpenStudy (anonymous):

can someone please help me with trigonometric substitutions?

OpenStudy (jdoe0001):

it's much easier if you just post the specifics

OpenStudy (anonymous):

I do that and no one answers me

OpenStudy (jdoe0001):

sometimes we may not know or are just caught up on something at the moment, we can always check back on material posted

OpenStudy (anonymous):

Use trigonometric substitution to write 3= radical (36-x^2) as a trigonometric function of theta, where -pi/2<theta<pi/2 given x=6 sin theta. Use the function to find the value of sin theta.

OpenStudy (jdoe0001):

hmmm not sure I follow that... can you post a quick screenshot of the material?

OpenStudy (anonymous):

OpenStudy (anonymous):

do you have any idea how to solve that?

OpenStudy (anonymous):

I'm incredibly lost.

OpenStudy (jdoe0001):

\(\bf 3 = \sqrt{(36-x^2)}\qquad \qquad x = 6sin(\theta)\\ \quad \\ 3 = \sqrt{(36-x^2)}\implies 3 = \sqrt{(36-(6sin(\theta))^2)}\\ \quad \\ \textit{squaring both sides}\\ \quad \\ (3)^2 = \left(\sqrt{(36-(6sin(\theta))^2)}\right)^2\implies (3)^2 = \sqrt{[36-(6sin(\theta))^2]^2}\\ \quad \\ 9=36-(6sin(\theta))^2\implies (6sin(\theta))^2=36-9\implies (6sin(\theta))^2=27\\ \quad \\ \textit{now taking square root to both sides}\\ \quad \\ \sqrt{(6sin(\theta))^2}=\sqrt{27}\implies 6sin(\theta)=\sqrt{27}\\ \quad \\ sin(\theta)=\cfrac{\sqrt{27}}{6}\)

OpenStudy (jdoe0001):

\(\bf \color{blue}{27 = 3\times 3\times 3\implies 3^2\times 3}\qquad thus\\ \quad \\ sin(\theta)=\cfrac{\sqrt{27}}{6}\implies sin(\theta)=\cfrac{\sqrt{3^2\times 3}}{6}\implies sin(\theta)=\cfrac{\cancel{3}\sqrt{ 3}}{\cancel{6}}\\ \quad \\ \implies sin(\theta)=\cfrac{\sqrt{ 3}}{2}\)

OpenStudy (anonymous):

thank you so much! I actually understood that!

OpenStudy (jdoe0001):

yw

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