update 02_day_data_types.md

02_Day_Data_types/02_day_data_types.md

@@ -51,26 +51,26 @@
 In the previous section, we mentioned a little bit about data types. Data or values have data types. Data types describe the characteristics of data. Data types can be divided into two:
 
 1. Primitive data types
-2. Non-primitive data types(Object References)
+2. Non-primitive data types (Object References)
 
 ### Primitive Data Types
 
 Primitive data types in JavaScript include:
 
- 1. Numbers - Integers, floats
- 2. Strings - Any data under single quote, double quote or backtick quote
+ 1. Numbers - integers, floats
+ 2. Strings - any data under single quote, double quote or backtick quote
  3. Booleans - true or false value
  4. Null - empty value or no value
  5. Undefined - a declared variable without a value
- 6. Symbol - A unique value that can be generated by Symbol constructor
+ 6. Symbol - a unique value that can be generated by Symbol constructor
 
 Non-primitive data types in JavaScript includes:
 
 1. Objects
 2. Arrays
 
 Now, let us see what exactly primitive and non-primitive data types mean.
-*Primitive* data types are immutable(non-modifiable) data types. Once a primitive data type is created we cannot modify it.
+*Primitive* data types are immutable (non-modifiable) data types. Once a primitive data type is created we cannot modify it.
 
 **Example:**
 
@@ -191,7 +191,7 @@ const PI = Math.PI
 console.log(PI)                            // 3.141592653589793
 
 // Rounding to the closest number
-// if above .5 up if less 0.5 down rounding
+// Round up if above 0.5, round down if less than 0.5
 
 console.log(Math.round(PI))                // 3 to round values to the nearest number
 
@@ -235,12 +235,14 @@ console.log(Math.log(10))       // 2.302585092994046
 console.log(Math.LN2)           // 0.6931471805599453
 console.log(Math.LN10)          // 2.302585092994046
 
-// Trigonometry
+// Trigonometry (the angle must be in radians)
+// If you want to use degrees, you have to first convert it to radians
+// Angle in radians = Angle in degrees x PI / 180
 Math.sin(0)
-Math.sin(60)
+Math.sin(1.05)
 
 Math.cos(0)
-Math.cos(60)
+Math.cos(1.05)
 ```
 
 #### Random Number Generator