Melody

Kitty has done it via formula.  There is nothing wrong with that.  Thanks Kitty.

CPhill hse done it very logically, he just forgot to mention that 2 of his isoscles triangle 'leg' angles adds up to one internal ocatgon angels.  His answer is the same as Kitty's.

I really like how you did that Chris.     

Are three wise men enough to convince you Chris ?     :)

I have added this to the "Great Answers To Learn From" sticky thread    Thanks Guys 

No you can not :)

if TanA+1/TanA = 2 , find the value of tanA^2+1/tan^2A

$$\\tanA+\frac{1}{tanA} = 2\\\\
\left(tanA+\frac{1}{tanA}\right)^2 = 2^2\\\\
tan^2A+\frac{1}{tan^2A}+2*tanA*\frac{1}{tanA}= 4\\\\
tan^2A+\frac{1}{tan^2A}+2= 4\\\\
tan^2A+\frac{1}{tan^2A}= 2\\\\$$

Kitty has found the 2nd quadrant answer.

there is also a third quadrant answer and that would be

180+60 = 240 degrees 

or

4pi/3 radians

the calculator is on the home page :)

I've got another idea.

The circumference is  pi* diameter.

pi is about 3

SO

If the circumference is 30 inches then the diameter must be about 30/3 = 10 inches (that is a little less than a foot)

Which of those is a bit less than 1 foot across ?

That is a great diagram and explanation Zac :)

Yours is good too DarkBlaze347                            

I like the answers that you are giving DarkBlaze347.  Askers should do some work for themselves :)

I enjoyed your you tube clip Dbg