Thread: Solve equation tanx=3sinx

Hi just worked through this question:

Solve the equation:


for

I get cos(x) = 1/3

and x = +- 70.5

The answer says it's also +- 180 which makes sense but i wondered how this second result can be found?

Thanks

Originally Posted by aceband

Hi just worked through this question:

Solve the equation:


for

I get cos(x) = 1/3

and x = +- 70.5

The answer says it's also +- 180 which makes sense but i wondered how this second result can be found?

Thanks

EDIT: Does your book also give x=0 as a solution?

As you have written it you are right but the book's answer suggest your limits are actually . This means are allowable

You are cancelling out sin(x) in the second step which is potentially equal to 0. Instead, solve this equation via factorising.







Either: (which is where -180,0,180 comes from)

or which you did


It is also interesting to note that this equation has a vertical asymptote at