Reply to Comments

Thanks for your comments. Actually, one of the answers to the poll is correct. It might help if you set your watch to that time. Try it.

References

Types of Angles | Different Types of Angles | TutorVista.com . (n.d.).Tutorvista.com - Online Tutoring, Homework Help for Math, Science, English from Best Online Tutor. Retrieved March 5, 2010, from http://www.tutorvista.com/content/math/geometry/angles_at_a_point/class9maths2.php

Angles Cartoons and Comics. (n.d.). CartoonStock - Cartoon Pictures, Political Cartoons, Animations.. Retrieved March 8, 2010, from http://www.cartoonstock.com/directory/A/Angles.asp

Geometry. (n.d.). Math is Fun - Maths Resources. Retrieved March 5, 2010, from http://www.mathsisfun.com/geometry/index.html

Kelly, K., & Zeman, A. (1997). Angles. Everything You Need To Know About Math Homework (Evertything You Need To Know..) (pp. 96-98). Cincinnati: Scholastic Reference.

Protractor Clipart. (n.d.).Educational Technology Clearinghouse . Retrieved March 8, 2010, from http://etc.usf.edu/clipart/25700/25799/protractor_25799.htm

Unit 11 Section 1 : Angle Measures. (n.d.). Centre for Innovation in Mathematics Teaching. Retrieved March 8, 2010, from http://www.cimt.plymouth.ac.uk/projects/mepres/book8/bk8i11/bk8_11i1.htm

front, t. t., & which, t. a. (n.d.). CHICOS. California HIgh school Cosmic ray ObServatory. Retrieved June 6, 2010, from http://www.chicos.caltech.edu/cla

Complementary and Supplementary Angles

Complementary Angles are angles that, when joined together, form a right angle (90°).

Look at the following example the two adjacent angles below form a right angle when added together. 40° + 50° = 90°.

source: (http://www.mathsisfun.com/geometry/complementary-angles.html)

If only one angle is given then the other angle can be found by subtracting. 90° - the given angle = the other angle. Look at the following example:

source: (Clipart ETC: http://etc.usf.edu/clipart/25700/25799/protractor_25799.htm)

Suppose angle A is 25°. So, to find angle B you would subtract. 90° - 25° = 65°

Supplementary Angles are angles that, when joined together, form a straight line (180°).

Look at the following example the two adjacent angles below form a supplementary angle when added together. 40° + 140° = 180°

source: (http://www.mathsisfun.com/geometry/complementary-angles.html)

Just like with the complementary angles, if only one angle is given then the other angle can be found by subtracting. But using 180°instead of 90°. 180° - the given angle = the other angle. Look at the following example:

source: (Clipart ETC: http://etc.usf.edu/clipart/25700/25799/protractor_25799.htm)

Suppose angle A is 85°. So, to find angle B you would subtract. 180° - 85° = 95°

How can you remember which is which? Easy! Think:

• "C" of Complementary stands for "Corner" (a Right Angle), and
• "S" of Supplementary stands for "Straight" (180 degrees is a straight line)

Now its your turn, try it yourself!

source: (Chichos Caltech: http://www.chicos.caltech.edu/classroom/pointer/diagrams.htm)

If angle ABC = 35

°, how many degrees is angle CBD?

If angle JHK = 87°, how many degrees is JHI?

Source: CSL cartoonstock (http://www.cartoonstock.com/directory/A/Angles.asp)