Radian measure- use found expression to find approx π

Okay, this question makes absolutely no sense.

I assumed π can only be 3.14 or 180degrees.

Question:
a. Given theta is small, write down an approximate expression for cos theta in form a+b theta+c theta².

Simple enough-
1-1/2theta²

b. Use your expression with theta=π/6 to find approx value for π.

All I find is 1-(π²/72) which is 0.863.

How can it be that the answer is 6√2-√3

On that note. Maybe, I’ll take an early day lol

Reply 1

Daniil.M

The answer 6√2-√3 is wrong. It is not even close to π.

You found 1-(π²/72). Now find the value of cos pi/6 which is √3/2. See where you can go from there

Reply 2

KingRich

Original post by Daniil.M

The answer 6√2-√3 is wrong. It is not even close to π.

You found 1-(π²/72). Now find the value of cos pi/6 which is √3/2. See where you can go from there

I took momentarily break watching YouTube and upon doing something tedious my brain fired up and realised as they’re approx it would help to find cos π/6 too.

at that point I got this far. I’m jus trying to recall how to solve radicals again lol

Reply 3

KingRich

Original post by Daniil.M

The answer 6√2-√3 is wrong. It is not even close to π.

You found 1-(π²/72). Now find the value of cos pi/6 which is √3/2. See where you can go from there