


TrigonometryUsing the Value of One Trig Function to Find AnotherIf the value of one trig function is known, any of the other trig functions can be calculated. ExampleSuppose α = tan θ is known. This situation can be represented by the following diagram. We set the adjacent side to length 1. Then using the definition of tangent, the opposite side must have length tan θ, thar is, α.
Using Pythagoras Theorem we find the hypotenuse is of length . Each of the three sides are now determined and and . Exercise 4Suppose α = sin θ is known. Find tan θ and cos θ in terms of α.
Exercise 5Suppose α = cos θ is known. Find tan θ and sin θ in terms of α. << Trigonometric Identities  Trigonometry Index  Measuring Angles (Degrees and Radians)>> 