Using [–] instead of [(-)] to indicate that a
number is negative
Entering an angle in
degre in radian mode
Indicating the order of operations incorrectly
by using parentheses
Entering the inverse
trigonometric notation
Placing the powers for trigonometric functions
ENGINEERING HACKS
Common
Input Errors with Your Calculator that You Probably Didn’ t Notice
by Dion Greg Reyes
E ngineers, whatever field you specialize in, have a universal best friend: your calculators. Almost all the time – when your fingers can no longer perform a trigonometric function – you depend on your life with the calculators in solving problems. But there will be cases that you will be faced with errors you didn’ t know you have made. And that could cost you a failing grade or even your job. Maybe even lives of people.
While there are so many kinds of calculators, here are the common input errors that you may have encountered in any calculator. It’ s best that you read your calculator manuals, but most likely you can find those input errors here.
Using [–] instead of [(-)] to indicate that a
number is negative
Common rookie error. You use the [–] to subtract, and [(-)] to denote a negative number. There is a difference. When you use [–] instead of [(-)] in the interior of an expression to denote a negative number, the calculator responds with the syntax error message.
Entering an angle in
degre in radian mode
In the calculator, trigonometric functions can be used with two modes: degree or radian. Just make sure that you are using the degree mode or radian mode, depending on what you’ re required. Changing the mode depends on the settings of your calculator.
Indicating the order of operations incorrectly
by using parentheses
In your calculator, – 3^2 is not the same as(– 3) ^2. The calculator first performs the operation in parentheses, then it squares the number. If there is a negative outside the parentheses, it first performs the squaring, then the operation of a negating a number. That’ s how crucial the order of operations is in evaluating expressions.
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Entering the inverse
trigonometric notation
Here’ s another: just because the trigonometric function is raised to a negative number, which you know is an inverse, it is not an exponent; in the calculator, the inverse of the cos( x) function is not 1 / cos( x). In short, but,
.
Placing the powers for trigonometric functions
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Photo Source: Davidson Math
Remember the order of operations? Yeah, that’ s it. All trigonometric functions hold this notational idiosyncrasy.