Estimating sine and tangent?

Question

How can I estimate the sine and tangent in a given triangle?

Answer 1

For any given triangle ABC with sides a, b and c.

Cos C = (a^2 + b^2 - c^2)/2ab This is the cosine rule.

Sin C =sqrt(1 - Cos^2 C). You may need to adjust the sign of the sign to match the triangle.

Answer 2

Assuming you are talking a right triangle, the tan is the ration of the side opposite to the side adjacent. For very small angles the sine is essentially the tangent.