Need Help 2007 ADA #33 & #34

[Bobby Fischer]

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(sorry about the formatting...best I can get it to do). My specific question might be if there are a set of rules I need to know to answer these 2 questions? They look totally unfamiliar:
33.
For all y, the cos y is equal to

A. sin

y

B. cos (

y + π)

C. sin (-

y)

D. sin

y + cos y

E. cos (-

y)

34.
The value of cos (π/3) equals the

value of

A. -cos (2

π/3).

B. cos (2

π/3).

C. cos (6

π/3).

D. -cos (5

π/3).

E. cos (4

π/3).

 

[theleatherwalle]

alright chess master i think we're gonna do a little trig review.

So if you ever set up a trig circle it sorta worked like this

0-90 everything is positive

90-180 only sin is positive

180-270 only tan is positive

270-360 only cos is positive

Now think about it. where is cos y equal to out of those answer choices.

This little chart i gave you should let you answer these two questions.

 

[Bobby Fischer]

alright chess master i think we're gonna do a little trig review.

So if you ever set up a trig circle it sorta worked like this

0-90 everything is positive

90-180 only sin is positive

180-270 only tan is positive

270-360 only cos is positive

Now think about it. where is cos y equal to out of those answer choices.

This little chart i gave you should let you answer these two questions.

Where is the chart? This young grasshopper really wants to figure these out.

 

[Bobby Fischer]

Where is the chart? This young grasshopper really wants to figure these out.

Never mind. Now I get it. Stupid question by me...👍

 

[theleatherwalle]

(sorry about the formatting...best I can get it to do). My specific question might be if there are a set of rules I need to know to answer these 2 questions? They look totally unfamiliar:
33.
For all y, the cos y is equal to

A. sin

y

B. cos (

y + π)

C. sin (-

y)

D. sin

y + cos y

E. cos (-

y)

34.
The value of cos (π/3) equals the

value of

A. -cos (2

π/3).

B. cos (2

π/3).

C. cos (6

π/3).

D. -cos (5

π/3).

E. cos (4

π/3).

I think what I wrote may have confused you. Okay, so the chart im referring to is what i wrote for the 0-90, 90-180 ect.

So memorize that chart. Its basically essential for any trig problem

So for problem 33 it says cos y is equal to what answer choice.

So lets remember something about cos y. Cos Y is only positive from 0-90 and 270-360...knowing that we can see that E is the answer. If you don't believe me, start plugging in numbers for Y and solving it against the other equations.

Now for the next problem I leave for you. Hint: pi/3 equal 60 degrees.