How do you find the values of all six trigonometric functions of a right triangle ABC where C is the right angle, given a=9, b=40, c=41?

1 Answer

See below:

Explanation:

Given that this is a right triangle, let's put side a along the positive xx axis, side b along the yy axis, and side c is the hypotenuse.

Now the question is Which angle are we concerned with? Is it angle A? Angle B? Or even the right angle, angle C?

Since we aren't given which angle, I'll work all 3.

The 6 trig functions are sin, cos, tan, csc = 1/sin, sec = 1/cos, cot = 1/tansin,cos,tan,csc=1sin,sec=1cos,cot=1tan (maybe you've learned SOHCAHTOA, or Sin = "Opp"/"Hyp", Cos = "Adj"/"Hyp", Tan = "Opp"/"Adj"sin=OppHyp,cos=AdjHyp,tan=OppAdj).

Angle A

Angle A has as its opposite side a, which means it's two sides are 1. along the yy axis and 2. the hypotenuse:

sin=9/41; csc = 41/9sin=941;csc=419

cos = 40/41; sec = 41/40cos=4041;sec=4140

tan = 9/40; cot = 40/9tan=940;cot=409

Angle B

Angle B has as its opposite side b, which means it's two sides are 1. along the xx axis and 2. the hypotenuse:

sin=40/41; csc = 40/41sin=4041;csc=4041

cos = 9/41; sec = 41/9cos=941;sec=419

tan = 40/9; cot = 9/40tan=409;cot=940

Angle C

Angle C is the right angle:

sin=1; csc = 1sin=1;csc=1

cos = 0; sec = "undefined"cos=0;sec=undefined

tan = "undefined"; cot = 0tan=undefined;cot=0