solve this equation for A in the range 0<A<360
tanA + cotA = 2secA
i found A= 30, 150, 210, 330 degrees and all of these results fit the tangent function i solved for. but the answer includes only A = 30 and 150 degrees. why is this?
Hello furor celtica
You can see a similar thing if you square both sides in a simple non-trig equation. For example:
The solution is, of course, . But if you square both sides:
And the value doesn't satisfy , but . But of couse, both and give the value .
So, always beware of squaring both sides of an equation: you'll sometimes introduce extra, unwanted solutions if you do.