Question

What is 4 cos x-2=0

Answer 1

Solve this as you would a "regular" equation. Add 2 to both sides and get 4 cos x = 2. Now divide both sides by 4 to get \[\cos(x)=\frac{ 1 }{ 2 }\]Uour job now is to find where (x) the cos is 1/2. You can look at a unit circle or if you don't have one we have to do it the long way, which is just as easy! We need to figure out which of our special triangles has the triple with a 1 and a 2 in it. that's a 30-60-90. The side opposite the 30 is 1, the side opposite the 60 is the square root of 3, and the hypotenuse is 2. Since cosine is the side adjacent to the angle over the hypotenuse, you know it looks like thishich angle is across from the square root of 3? The 60, right? So the angle measure is 60 degrees or pi/3.