SOLUTION: determine the specified trigonometric ratio for each special angle. 1. cos(11pi/6) 2.cot(5pi/4) 3.sec(4pi/3)

Algebra.Com
Question 1158031: determine the specified trigonometric ratio for each special angle.
1. cos(11pi/6)
2.cot(5pi/4)
3.sec(4pi/3)

Found 2 solutions by josmiceli, Theo:
Answer by josmiceli(19441)   (Show Source): You can put this solution on YOUR website!
(1)



This is in the 4th quadrant & the cos is positive

-----------------------------------
(2)



This is in the 3rd quadrant & cot is positive (-) / (-) = (+)


------------------------------------
(3)



This its in the 3rd quadrant & the sec is negative


---------------------------
Get a 2nd opinion if needed


Answer by Theo(13342)   (Show Source): You can put this solution on YOUR website!
11pi/6 radians * 180 / pi = 11*180/6 = 11*30 = 330 degrees.
the angle is in the fourth quadrant.
the reference angle = 360 - 330 = 30 degrees.
cosine of 30 degrees = sqrt(3)/2
since the angle is in the fourth quadrant, cosine is positive, therefore the cosine of 330 degrees is sqrt(3)/2.

5pi/4 radians * 180 / pi = 5 * 180 / 4 = 5 * 45 = 225 degrees.
the angle is in the third quadrant.
the reference angle is 225 - 180 = 45 degrees.
cotangent of 45 degrees = 1 / tangent of 45 degrees = 1
since the angle is in the third quadrant, cotangent is positive, therefore the cotangent of 225 degrees is 1.


4pi/3 radians * 180 / pi = 4 * 180 / 3 = 4 * 60 = 240 degrees.
the angle is in the third quadrant.
the reference angle is 240 - 180 = 60 degrees.
secant of 60 degrees = 1 / cosine of 60 degrees = 1 / (1/2) = 2
since the angle is in the third quadrant, the secant is negative, therefore the secant of 240 degrees = - 2

to confirm, put your calculator in radian mode and do the following:
cos(11pi/6)
1/tan(5pi/4)
1/cos(4pi/3)

you will get:
cos(11pi/6) = .8660254038
1/tan(5pi/4) = 1
1/cos(4pi/3) = -2

enter sqrt(3)/2 in your calculator to find that it is equivalent to .8660254038 in decimal format.


RELATED QUESTIONS

1.)Using radians, find the period of each function. Then graph. a.) y=cos(4theta+5pi/3)... (answered by stanbon)
Compute or solve the following in radians without a calculator: a. sec((4pi)/3) b.csc (answered by Alan3354)
Find the values of Sin, Tan, Cos, Cot, Sec, and Csc for the argument. 1. 5pi/4 2.... (answered by addingup,MathTherapy,Alan3354)
Find the solutions 18cot2x - 6 = 0 in the interval from 0 to two pi inclusive. a) pi/3,... (answered by lwsshak3)
What is exact value of sec(5pi/6)cos(7pi/4)- cot(-pi/3) Thank you. (answered by ad_alta)
Find the other five trigonometric functions for each of the following given: 1. sin ¢ =... (answered by Alan3354)
What values for, theta(0<=theta<=2pi) satisfy the equation? tan^2 theta=-3/2 sec theta (answered by stanbon)
for each of the following find the reference arc and the values of cosine and sine of... (answered by ikleyn,josgarithmetic)
solve 2sin x + sqrt 3<0 for 0<= x < 2pi a)4pi/3 < x < 5pi/3 b)2pi/3 < x < 4pi/3... (answered by stanbon)