Need math wiz help ASAP!!!

[JoeC]

Hey guys, I really need some help ASAP on some college trig. (math 103)..

There are three problems i CANNOT understand. If some peeps would like to help me I would be VERY thankful.

Notes: i cant use the pi symbol so i will just say pi.
1. What is the period of the function y=4cos(pi x/4)-3sin(pi x/10)

2. if the area of a sector is 450 inches squared and it cuts an arc of length 60 in on a circle, find the radius of the circle and the central angle, measured in radians.

the equation to find area of a sector is A = 1/2 r squared theta.

the equation to find the arc length is S = r(theta)

r = radius.
if you need it *im unsure*.. but to convert degrees to radians, you multiply by pi/180.

3. Give an exact value for the given expression. Note the angle given is in radians. Arctan (sin14)


If there are some people out there that will help me, I would thank you SO much and find a way to return the favor on the forum some day.

 

[johnathan1]

Ugh, some of that looks familiar, I can almost remember how to do it, but all I know is what I learned in Trig/Pre-calc senior year. :icon_conf

 

[CFSapper]

i can give you the anwer to 3 for sure.
and im pretty sure i can get the anwser for number one

but i dont know if you want just the anwser

all the anwers i would get are from my graphing calculator

 

[JoeC]

If you have a high enough graphing calculator you can find the answer and then show the steps on how the calculator found it *ti-89+* i believe. I need exact answer for #3.. i cant figure it out. I found the 1st and 2nd one out though..

 

[trydrew]

I took AP Calc my Junior year of HS. Obviously that was too early. It would be very easy for me to relearn it but relearn it I must.

 

[JoeC]

i stopped at alg. 3/4 my junior year. Tested into trig for college and its been a nightmare.. So any one have a clue how to solve 3??

arctan(sin 14) theta is in radians. I need an exact answer, no decimal approximation. The thing i do NOT understand is this..

arctan(sin 14).. when converting 14 rad to degrees you multiple by 180/pi which gives you 2520/pi, but if you plug arctan(sin 2520/pi) it gives you a different answer. I went to figure out what quadrant 14 radians was in, and it came out to be 802 degrees in quadrant 1 (82 degrees).. so i thought I would find the answer if I converted 82 degrees back to radians which is 82(pi/180).. giving me 82pi/180 or 41pi/90.. and if i plug that into arctan(sin 41pi/90) i get like 1.43... which isn't the same as arctan(sin14)...


ANY ONE?? lol.. My professor will NOT help me with this.. I've asked him.

 

[Wills7MGTE]

God enuff with the Math thats what the EMS is for............