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Mathematics 19 Online
OpenStudy (anonymous):

Use basic identities to simplify the expression.

OpenStudy (anonymous):

OpenStudy (noelgreco):

Convert each of the three trig functions to sin and cos.

OpenStudy (anonymous):

How do I do that? I don't really understand how to work with identities in the 1st place.

OpenStudy (noelgreco):

\[\sec \theta=\frac{ 1 }{ \cos \theta }\] etc.

OpenStudy (anonymous):

Okay so cscu=1/sinu cot=cosu/sinu

OpenStudy (jdoe0001):

yes $$\bf \frac{csc(\theta)cot(\theta)}{sec(\theta)}\\ \large \cfrac{ \frac{1}{sin(\theta)}\frac{cos(\theta)}{sin(\theta)} }{ \frac{1}{cos(\theta)} } \implies \cfrac{ \frac{cos(\theta)}{sin^2(\theta)} }{ \frac{1}{cos(\theta)} }\\ \text{now keep in mind that}\\ \cfrac{\frac{a}{b}}{\frac{c}{d}} \implies \frac{a}{b} \times \frac{d}{c} $$

OpenStudy (jdoe0001):

thus \(\bf \large \cfrac{ \frac{cos(\theta)}{sin^2(\theta)} }{ \frac{1}{cos(\theta)} } \implies \frac{cos(\theta)}{sin^2(\theta)} \times \frac{cos(\theta)}{1}\)

OpenStudy (jdoe0001):

so, what would that give you?

OpenStudy (anonymous):

csc2u? Omg I don't really know. I'm trying to follow it but the last part is throwing me off. I don't understand how you'd multiply it out to get one of the choices from above.

OpenStudy (jdoe0001):

hmmm, what part confused you?

OpenStudy (anonymous):

The final step before getting the final answer after rearranging the equation and doing a/b*d/c.

OpenStudy (jdoe0001):

yes anything wrong with \(\bf \huge \cfrac{\frac{a}{b}}{\frac{c}{d}} \implies \frac{a}{b} \times \frac{d}{c}\ \ ?\)

OpenStudy (jdoe0001):

my 2 fractions were \(\bf \large \cfrac{ \frac{cos(\theta)}{sin^2(\theta)} }{ \frac{1}{cos(\theta)} }\) thus

OpenStudy (anonymous):

No I understood that. It's: cos(θ)sin2(θ)×cos(θ)1 Is it cos2u/sin2u which means it's sec2u? I'm not sure how to multiply that part out is what I meant.

OpenStudy (anonymous):

Whoops cosu/sin2u*cosu/1 not cos(θ)sin2(θ)×cos(θ)1

OpenStudy (jdoe0001):

hmm, multiplication of rationals is just across the board numerator by numerator and denominator by denominator

OpenStudy (anonymous):

Yeah I got cos2u/sin2u which doesn't fit the choices: sec2u, cot2u, csc2u, and 1

OpenStudy (jdoe0001):

hmm well, we haven't multiplied across yet :)

OpenStudy (jdoe0001):

$$\bf \cfrac{ \frac{cos(\theta)}{sin^2(\theta)} }{ \frac{1}{cos(\theta)} } \implies \cfrac{cos(\theta)}{sin^2(\theta)} \times \cfrac{cos(\theta)}{1} \implies \cfrac{cos^2(\theta)}{sin^2(\theta)} $$

OpenStudy (jdoe0001):

so as you said =>\(\text{Okay so cscu=1/sinu } \\ \bf \text{cot=cosu/sinu}\) so what do you think you'd simplify the rational to?

OpenStudy (anonymous):

cot2u

OpenStudy (jdoe0001):

\(\bf \cfrac{cos^2(\theta)}{sin^2(\theta)} \implies cot^2(\theta)\)

OpenStudy (anonymous):

Yayy! Thanks so much for having the time and patience to put up with me! I actually grasp the concept much better now. :O

OpenStudy (jdoe0001):

yw

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