Are the following true or false & why?

cos(-175°) = cos(175°)

cos(32°) = sin(58°)

sin(π/3) = 1/sec(π/3)

cos(2π/3) = cos(4π/3)

Question

Are the following true or false & why?

cos(-175°) = cos(175°)

cos(32°) = sin(58°)

sin(π/3) = 1/sec(π/3)

cos(2π/3) = cos(4π/3)

anonymous · Answer

first one is true because cosine is even

anonymous · Answer

that is to say 
$$\cos(x)=\cos(-x)$$

anonymous · Answer

hello anwar

anonymous · Answer

Hi :)

anonymous · Answer

second one is true because they add up to 90

anonymous · Answer

third one is false because the reciprocal of sine is cosecant, not secant.

anonymous · Answer

how am i doing so far?

anonymous · Answer

seems right

anonymous · Answer

and 4th is true

anonymous · Answer

really?  why?

anonymous · Answer

CAST RULE!

anonymous · Answer

2pi/3 and 4pi/3 , both have relative angles of pi/3 with the x axis

anonymous · Answer

and cos is negative in both 2 and 3rd quadrants

anonymous · Answer

what the monkey is cast rule?

anonymous · Answer

thing its something similar to ASTC

anonymous · Answer

Please tell me, what is the cast rule? lol!

anonymous · Answer

i mean i see that they are the same from drawing a circle.  so the answer is true.  so i am not casting any doubts

anonymous · Answer

it tells you when the trig functions are positive going counterclockwise from the fourth quadrent labelling it C, then A, then S, T. C= cosine, A all, S = sine, T tan

anonymous · Answer

Sorry for all of the trouble I'm causing! I just really don't understand any of this :(
But you guys are really helping out!!!

anonymous · Answer

yeh I wouldnt worry about this cast rule thing, its the first time I have ever heard of it, ever

anonymous · Answer

it will only confuse you

anonymous · Answer

http://www.physics.uoguelph.ca/tutorials/trig/trigonom2.html