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January 25, 2015

January 25, 2015

Posted by **Jaime** on Sunday, July 13, 2008 at 7:08pm.

Tan(-3p/4)=

Sec(2p/3)=

Csc(7p/4)=

Cot(11p/6)=

p=pie

- Trignonmetry -
**Damon**, Sunday, July 13, 2008 at 7:36pm-3pi/4 = 2pi -3pi/4 = + 5 pi/4

so you really want tan 5pi/4 which is pi/4 below the -y axis

x = -1

y = -1

y/x = tangent = 1

sec 2 pi/3 = 1/cos 2 pi/3

that angle is between pi/2 and pi, second quadrant

pi - 2 pi/3 = pi/3 above -y axis

x = -1

y = +sqrt 3

sqrt(x^2+y^2) = hypotenuse = 2

so

cos(2pi/3) = -1/2

sec(2 pi/3)= -2

etc. draw the triangles

- Trignonmetry -
**Reiny**, Sunday, July 13, 2008 at 7:39pmYou should be familiar with the trig ratios of the 30-60-90º triangle as well as the 45-45-90º triangle

pi/4 radians <-----> 45º

pi/3 radians <-----> 60º

pi/6 radians <-----> 30º

all your given angles are multiples of these.

I will do the last one

cot(11pi/6) = 1/tan(11pi/6)

11pi/6 is in the fourth quadrant, in the fourth quadrant the tangent is negative, so the cotangent is negative.

The angle is pi/6 away from the x-axis, so the 'angle in standard position' is pi/6

tan pi/6 = 1/√3, so cot pi/6 = √3

then cot(11pi/6) = -√3

do the others the same way.

- Trignonmetry -
**Andrea**, Sunday, April 8, 2012 at 9:09pmWhat is sin of 660?

And

What is csc(-2pi)/3?

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