Sunday, October 18, 2009

Reflection: Introduction to Trigonometry

This week seems to have been quite easy. In section 1 we learned about the measurement of angles, and in section 2 we learned about sectors of circles. Today, I’ll be going over section 1.

In Advanced Math, Angles will be measures as either degrees (°) or radians (rad or no symbol).

NOTE: IF YOU DO NOT HAVE A SYMBOL, IT IS ASSUMED TO BE RADIANS. 

In Geometry, you most probably measured everything in degrees.  Degrees can be written two ways in decimal degrees or in DMS form (degrees, minutes, seconds)

It is usually preferred that you state degrees in DMS form. 

Convert 19.64° to DMS form.

There are 2 methods for converting:

METHOD 1:

1. Take your integer unitsand write them down as whole degrees.

19°

2. Multiply everything behind the decimal (including the decimal) by 60.

.64*60 =38.4

3. Write your integer units down as minutes,

19°38’

4. Repeat step 3 & 4 to find seconds.

.4*60 = 24

Final Answer: 19°38’24”

Note: If  you have decimal places after all of this, it is okay to put your seconds value as a decimal.

METHOD 2: (Will only work on TI-80’s series calculators)

1. Type in the decimal degrees:

DECIMAL DEGREES

2. Press 2nd>Apps  to get to the Angle menu, and scroll down to >DMS (0ption 4). Press enter.

ANGLE MENU

3.Press enter once again and Voila!

DMS DEGREES

 

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One Radian is 180/╥ degrees and one degree is ╥/180 but there is a similarly easy way to convert Radians to degrees.

1. Type in radians:

RADS

2. Get to Angle Menu and select degrees (option 1):

ANGLE MENU

3. Press enter:

DEGREES

 

Hope this helps!

Dinidu Perera, the Calculator Guru

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