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Mathematics 10 Online
OpenStudy (aaronandyson):

Trig Question.

OpenStudy (aaronandyson):

\[\frac{ cosec A }{\cot A + \tan A }=\cos A\]

OpenStudy (aaronandyson):

@campbell_st

OpenStudy (campbell_st):

ok... so work on the denominator cot = cos/sin and tan = sin/cos so cot + tan = cos/sin + sin/cos same as before... common denominator and multiply... then cross multiply in the numerator what would you get..?

OpenStudy (aaronandyson):

cscAsecA

OpenStudy (campbell_st):

lets keep it as \[\frac{1}{sonAcosA}\] is that ok..?

OpenStudy (campbell_st):

oops sin not son

OpenStudy (aaronandyson):

Okay.

OpenStudy (campbell_st):

so the numerator can be written as cosecA = 1/sinA is that ok..?

OpenStudy (aaronandyson):

yes

OpenStudy (aaronandyson):

1/sinA

OpenStudy (campbell_st):

careful flip and multiply \[\frac{1}{sinA}\times \frac{sinAcosA}{1} = ?\]

OpenStudy (campbell_st):

oops I made a mistake earlier it should read \[\frac{cosecA}{\frac1{sinAcosA}} = \frac{1}{sinA} \div \frac{1}{sinAcosA}\] opps sorry about the typo

OpenStudy (campbell_st):

that will now allow you to get the required solution

OpenStudy (aaronandyson):

I didn't get..

OpenStudy (campbell_st):

ok... so are you happy \[cosA + tanA = \frac{1}{sinAcosA}\]

OpenStudy (aaronandyson):

I got that.

OpenStudy (campbell_st):

ok so the problem can be written as \[\frac{cosecA}{costA + tanA} = \frac{cosecA}{\frac{1}{sinAcosA}}\] is that ok..?

OpenStudy (aaronandyson):

yes..

OpenStudy (campbell_st):

ok... I'll now change the numerator \[\frac{cosecA}{\frac{1}{sinAcosA}} = \frac{\frac{1}{sinA}}{\frac{1}{sinAcosA}} ~~or~~ \frac{1}{sinA} \div \frac{1}{sinAcosA}\] is that ok..?

OpenStudy (aaronandyson):

yes..

OpenStudy (campbell_st):

ok... so flip the 2nd fraction and multiply... what do you get...?

OpenStudy (campbell_st):

\[\frac{1}{sinA} \times \frac{sinAcosA}{1} =?\]

OpenStudy (aaronandyson):

cosA

OpenStudy (campbell_st):

great... so you can do this stuff...

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