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Mathematics 11 Online
Shadow:

Solving for theta

Shadow:

\[\cot \theta \cos^2 \theta = 2 \cot \theta \] @Vocaloid

Shadow:

@SmokeyBrown @zarkam21 any idea on the approach for this

SmokeyBrown:

Well, one thing you can do as a first step could be to divide both sides by cot(theta). This leaves us with cos^2=2

SmokeyBrown:

From there, I think you'd take the square root of both sides, to get cos = sqrt(2). Then you can do the inverse cosine to find the value of theta

woolyfrog:

wow you must be a genius SB

SmokeyBrown:

Nah, not at all

Shadow:

\[\cos ^{-1} = \sqrt2\]

Shadow:

?

Shadow:

for theta

SmokeyBrown:

Oh, sorry I was unclear. inverse cosine wouldn't be equal to sqrt(2). You would take the inverse cosine of sqrt(2) to find the value of theta.

Shadow:

\[\cos \theta = \sqrt 2\] \[\theta = \cos ^{-1} (\sqrt2)\] Does that fall in the unit circle?

Shadow:

yeah I misstyped that

Shadow:

It's supposed to fall between: \[0 \le \theta \le 2 \pi\]

SmokeyBrown:

Oh, that's weird. Yeah, cosine can only go up to 1 on the unit circle, but sqrt(2) is greater than 1...

Shadow:

Undefined?

Shadow:

Cause you can't grab the arc cos of values outside of the domain, when working within the unit circle.

SmokeyBrown:

That makes sense. I guess the value would be undefined then.

Shadow:

Alright, ty

SmokeyBrown:

np

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