Thread: trig help please!!!

1. trig help please!!!

Solve the equation:

π-3arccosθ=0

all i understand is arccosθ=0 means cos0=θ

but i'm getting confused when there is a value multiplying arc

the answer is arccosθ=π/3,θ=cosπ/3 =1/2

2. $\displaystyle \pi-3Cos^{-1}\theta=0$

$\displaystyle \pi=3Cos^{-1}\theta$

$\displaystyle \frac{\pi}{3}=Cos^{-1}\theta$

$\displaystyle Cos^{-1}\ is\ the\ inverse\ operation\ to\ Cos$

$\displaystyle \theta=Cos\frac{\pi}{3}$

3. Originally Posted by ladythugette
Solve the equation:

π-3arccosθ=0

all i understand is arccosθ=0 means cos0=θ

but i'm getting confused when there is a value multiplying arc

the answer is arccosθ=π/3,θ=cosπ/3 =1/2
this is a poorly posed equation ... the input for an inverse trig function is normally a trig ratio, not an angle, because the output of the arccos function is an angle. $\displaystyle \theta$ represents an angle.

using $\displaystyle x$ instead of $\displaystyle \theta$ ...

$\displaystyle \pi - 3\arccos{x} = 0$

$\displaystyle \arccos{x} = \frac{\pi}{3}$

$\displaystyle x = \cos\left(\frac{\pi}{3}\right) = \frac{1}{2}$