## Your Questions About Odd Calculator

Jenny asks…

## Even-Odd Properties?

Use the even-**odd** properties to find the exact value of each trig expression below. DO NOT USE a **calculator**.

(1) cos(-30 degrees)

(2) sin(-135 degrees)

(3) csc(-pi/4)

### admin answers:

(1) cos(-30 degrees) = cos(30) = (√3)/2

(2) sin(-135 degrees) = -sin(135) = -sin(45) = -(√2)/2

(3) csc(-pi/4) = 1/sin(-pi/4) = -1/sin(pi/4) = -1/(1/√2) = -√2

Charles asks…

## Common TI-89 calculator problem or no?

My TI-89 graphing **calculator** started acting strange about two days ago. the screen is vertically split into two where the left looks normal and then the right side is MUCH darker. Adjusting the contrast to see the darkened side results in the left side being completely invisible. I replaced the batteries and that obviously wasn’t the problem. I can’t download games or anything for that matter on to this type of **calculator** so there isn’t a game that’s messing up the memory. It hasn’t touched (or been near) water and it hasn’t been dropped. It’s only a few years old. So what may be the cause of this **odd** phenomena? Is there a safe (yet effective) way to reverse the problem?

### admin answers:

That has never happened to me. Something might have just happened inside the calculator with the screen causing it to look like that. You should try out their website or something. (if they have one.)

Thomas asks…

## need help with my scientific calculator please?

hi guys just a quick question. i know how to use the **calculator** to calculate the pH but i can’t remember how to punch in times by **odd** number exa..(^-7)

pH = –log [H3O+]

= –log (1.0 x 10^-7)

now i have the old school Casio **calculator**

http://i17.ebayimg.com/06/i/001/3b/5e/f267_1.JPG

thanks for your help.

hmm i get that but how do i punch in ^-7 on my **calculator**?

thanks i just found the e on my old **calculator**…please double check if i’m right from the pic link i put up….i pressed (shift) then (In) its placed right next to the log button

### admin answers:

You got it its -log( 1.0 x 10^(-7))

Or if your calculator has capital E

then

-log(1.0 X 10E-7)

Joseph asks…

## Strange pattern in the calculator number sequence?

Doing some work with number sequence here is what I found.

the **calculator** number sequence is like this from 0 to 9

7 8 9

4 5 6

1 2 3

The catch is, when you add three consecutive numbers in the exactly opposite and flipped direction, the sum is always a constant.

check this..

741+369 = 1110

789+321= 1110

diagonally 951+159=1110

357+753=1110

even these complicated patterns..

645+465=1110

478+632=1110

421+689=1110

639+471=1110

958+152=1110

ive tried all and they remain the same..

Surprisingly **odd** 😛 .. any clues why ?

### admin answers:

It happens that any line through the 5 intersects 2 numbers that add up to 10. There are 4 pairs [7,3 8,2 9,1 6,4] so as long as you do a pattern symmetrical around the 5 (or using 5 in the same place in each pattern as you have done), you are always going to get 1110 adding two lots of 3 digits. If you used 4 digit sequences you’d get 11110 and 5 digit sequences 111110 and so on…

James asks…

## Is this function even,odd, or neither?

A) x sin x

B) cosx sinx

I know how to do it with a **calculator**, but they are forbidden on tests. So i need to know how to do this WITHOUT a **calculator**.

### admin answers:

Well to check it you have to calculate f(-x) and compare it to f(x).

So, if f(x)=f(-x) => even

if f(x)=-f(x) => odd

And if none is true then it’s neither.

So for

A) f(x)=x*sinx

f(-x)=-x*sin(-x) since sin(-x)=-sinx f(-x)=-x*(-sinx) f(-x)=xsinx=f(x) => even

B) f(-x)=-sinx*cosx=-f(x) => odd

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