====Objective:====

Learn the basics of the Racket Language and functional programming in general.

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====Preparation:====

Download the latest version of DrRacket from [[http://racket-lang.org]] and install it on your computer.  Versions are available for Windows, Mac OS X, and Linux.

Please also take a look at [[cs330_f2016:turnin|how to turn in your assignments]]. 

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====Deliverables:====

For this lab, you will need to implement the following functions and data structures in Racket:
  * ''sum-coins''
  * ''degrees-to-radians''
  * ''sign''
  * ''new-sin''

=== sum-coins ===
<code racket>
(define (sum-coins pennies nickels dimes quarters) ...)
</code>
where ''pennies'', ''nickels'', ''dimes'', and ''quarters'' are all non-negative numbers and the value returned is the total value of the coins in cents.

=== degrees-to-radians ===
<code racket>
(define (degrees-to-radians angle) ...)
</code>
where ''angle'' is a number representing a value represented in degrees and the value returned is the equivalent representation in radians.  (For those who have forgotten their trig: radians = degrees / 180 * PI.)

=== sign ===
<code racket>
(define (sign x) ...)
</code>
where ''x'' is a number and the value returned is -1, 0, or 1 depending on whether ''x'' is negative, zero, or positive respectively.

=== new-sin ===
<code racket>
(define (new-sin angle type) ...)
</code>
where ''angle'' is a number representing either degrees or radians, type is either '''degrees'' or '''radians'' (a symbol) indicating how ''angle'' is represented, and the value returned is the sin of ''angle''.

Hint: use ''symbol=?'' to test for symbol equality: ''(symbol=? x 'degrees)''.

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====Notes:====

You **do not** need to bulletproof the code to enforce proper inputs.  
Your code only needs to return correct values given correct inputs.

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====Hints:====

Try clicking on the Step button to walk through your code and watch the equivalent sequence of substitutions that are performed.