How do you find the exact value of the six trigonometric functions of the angle whose terminal side passes through (x,4x)?

1 Answer
May 10, 2017

sinθ=417, cosθ=117, tanθ=4,

cotθ=14, secθ=17, cscθ=174

Explanation:

As the terminal side passes through (x,4x), we have y=4x and hence its distance from origin is x2+(4x)2=x2+16x2=x17

Now consider the diagram below for a typical θ, whose six trigonometrical ratios are

sinθ=yr, cosθ=xr, tanθ=yx and

cotθ=xy, secθ=rx, cscθ=ry

enter image source here

As we have y=4x and r=x17,

the six trigonometric ratios are

sinθ=4xx17=417, cosθ=xx17=117,

tanθ=4xx=4, cotθ=x4x=14,

secθ=x17x=17, cscθ=x174x=174