Another identity problem...

cot(x)=-sqrt(3)/3

Step-by-step explanation:

I'm going to use the Pythagorean Identity sin^2(x)+cos^2(x)=1 to find the sine value since cotangent value is the cosine value over sine value.

Plug in:

sin^2(x)+(-1/2)^2=1

Simplify:

sin^2(x)+1/4=1

Subtract 1/4 on both sidea:

sin^2(x)=3/4

Square root both sides:

sin(x)=sqrt(3)/2. [Sine is positive since x is in 2nd quadrant]

cot(x)=(-1/2)/(sqrt(3)/2))

cot(x)=-1/sqrt(3)

Rationalize denominator by multiplying by sqrt(3)/sqrt(3):

cot(x)=-sqrt(3)/3

cot(x)=

-13

step-by-step explanation:

f(x)=2x-5 for f(-4)

f(-4)   means let x=-4

f(-4) = 2(-4) -5

f(-4) =-8-5

      = -13