Question
Cos180* - Sin90* + Cot45* - Csc30* - Sec240* - Tan315*
How do I do this?
How do I do this?
Answers
Reiny
all these are standard angles for which you should know the trig ratios
cos 180 = -1 , look at the cosine curve
sin 90 = 1 , look at the sine curve
cot 45 = 1/tan45 = 1/1 = 1 , look at your 45-45-90 triangle
csc 30 = 1/sin30 = 1/(1/2) = 2 , look at the 30-60-90 triangle
sec 240 = 1/cos240 = - 1/cos60
= -1/(1/2) = -2 , using the CAST rule and 30-60-90 triangle
tan 135 = -tan45 = -1
now just add them up
cos 180 = -1 , look at the cosine curve
sin 90 = 1 , look at the sine curve
cot 45 = 1/tan45 = 1/1 = 1 , look at your 45-45-90 triangle
csc 30 = 1/sin30 = 1/(1/2) = 2 , look at the 30-60-90 triangle
sec 240 = 1/cos240 = - 1/cos60
= -1/(1/2) = -2 , using the CAST rule and 30-60-90 triangle
tan 135 = -tan45 = -1
now just add them up
Steve
these are all standard angles you should know by heart. It will save you a lot of trouble working them out all the time.
-1 - 1 + 1 - 2 + 2 + 1 = 0
It also involves knowing the signs of the trig functions in the various quadrants, and how to figure the reference angle.
Also, lose the capitalization.
-1 - 1 + 1 - 2 + 2 + 1 = 0
It also involves knowing the signs of the trig functions in the various quadrants, and how to figure the reference angle.
Also, lose the capitalization.