How do you evaluate tan1(0) without a calculator?

1 Answer
Dec 1, 2016

θ=0

Explanation:

Find tan1(0) without a calculator.

tan1(0) refers to the ANGLE whose tangent equals zero.

Recall the identity tanθ=sinθcosθ

If tanθ=0, then the numerator of sinθcosθ must also equal zero.

So, sinθ=0.

Referring to the unit circle, the angles with a sine of zero are
θ=0,π.

BUT, IT'S A BIT MORE COMPLICATED!

The range of tan1 (also called arctan) is π2 to π2.

In other words, the only "allowed" values of tan1 fall within this range. So, the the answer θ=π is not allowed, and the answer to the problem tan1(0) is θ=0