Math Is Fun Forum

  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 2006-07-04 22:07:54

RickyOswaldIOW
Member
Registered: 2005-11-18
Posts: 212

Radian Mode

Does anyone know how I can switch my calculator to radian mode?  It's a Casio ƒx-83WA.

If no one can then maybe you can tell me if I've worked this out correctly?

circle.jpg
(The image might not show up for a while, not sure why).

I need to work out the perimeter of the shaded area.
I started by taking the triangle and spliting it down the middle to make 2 right angled triangles, angle 0.8 and Hypotenuse 9 (call the triangle ABC where Hypotenuse is BC). 
AC = 9Sin0.8 = M

Therefore, the length of the chord from the image is 2M.  Since the arc is 1.6

2M+1.6 = Perimeter

I cannot find M since I cannot figure out how to put my calculator into radian mode but I looked at the answer at the back of the book.

2M+1.6 = 27.3
2M = 25.7
M = 12.85

I know from a previous example that 10Sin0.8 = 7.174 so I'm guessing that my answer is wrong because of the difference.

Last edited by rickyoswaldiow (2006-07-04 22:16:54)


Aloha Nui means Goodbye.

Offline

#2 2006-07-04 22:54:47

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,711

Re: Radian Mode

Good logic, and nearly right. You just forgot to multiply 1.6 by 9 smile

The sine of 0.8 is 0.7173561... (when in trouble use our Scientific Calculator or Function Grapher and Calculator)

So the chord is 2 * 9 * 0.7173561 = 12.9124
And the arc is 9*1.6 = 14.4

So the total perimeter is 27.3124


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

Offline

#3 2006-07-05 05:55:48

RickyOswaldIOW
Member
Registered: 2005-11-18
Posts: 212

Re: Radian Mode

because the angle in radians is 1.6 when the radius is 1? I was unsure of this but thanks for pointing it out wink

Funny:

2M+1.6 = 27.3

Is this a coincidence?

Last edited by rickyoswaldiow (2006-07-05 05:56:47)


Aloha Nui means Goodbye.

Offline

#4 2006-07-06 02:31:30

George,Y
Member
Registered: 2006-03-12
Posts: 1,379

Re: Radian Mode

just find "mode" button and press it.


X'(y-Xβ)=0

Offline

#5 2006-07-11 23:56:56

RickyOswaldIOW
Member
Registered: 2005-11-18
Posts: 212

Re: Radian Mode

Thanks George smile

For any with the same question, you need to press the mode button twice and radian mode is the second option there.  There are 3 pages of modes but I could not figure this out sad


Aloha Nui means Goodbye.

Offline

#6 2006-07-13 01:50:36

George,Y
Member
Registered: 2006-03-12
Posts: 1,379

Re: Radian Mode

If you need to get a result in emergency.
try this
x(rad)=180°x/Pi

or get a users manual click here


X'(y-Xβ)=0

Offline

Board footer

Powered by FluxBB