Find Six Trigonometric Functions of Theta

[nycmathguy]

Section 4.4
Question 9b

Question 9b

I can drop a perpendicular from the point (-8, 15) to the line y = 0 to form a right triangle. The given point gives me the value of x and y. To find the hypotenuse, I use a^2 + b^2 = c^2. Doing so, I found the hypotenuse to be 17.

Note: Must know where the trig functions are positive and negative on the xy-plane.

Answer:

sin (theta) = 15/17

cos (theta) = -8/17

tan (theta) = 15/8

csc (theta) = 17/15

sec (theta) = -17/8

cot (theta) = 8/15

Yes?

 

[MathLover1]

in Q II
tan (theta) = -15/8
cot (theta) = -8/15

 

[nycmathguy]

in Q II
tan (theta) = -15/8
cot (theta) = -8/15

Can "ALL STUDENTS TAKE CALCULUS" help in terms of remembering the signs for trig functions?

A for quadrant 1 = all trig functions are positive.

S for quadrant 2 = all trig functions are negative except for sine.

T for quadrant 3 = all trig functions are negative except for tangent.

C for quadrant 4 = all trig functions are negative except for cosine.

You say?

 

[MathLover1]

good

will be easier to memorize sin and cos, everything else easy to determine when you know identities

 

[nycmathguy]

good

will be easier to memorize sin and cos, everything else easy to determine when you know identities

Ok.