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Curriculum Outcomes
Geometry: Develop spatial sense.
5. Solve problems that involve parallel, perpendicular and transversal lines, and pairs of angles formed between them.[C, CN, PS, V]
6. Demonstrate an understanding of angles, including acute, right, obtuse, straight and reflex, by:
Geometry: Develop spatial sense.
5. Solve problems that involve parallel, perpendicular and transversal lines, and pairs of angles formed between them.[C, CN, PS, V]
6. Demonstrate an understanding of angles, including acute, right, obtuse, straight and reflex, by:
- drawing
- replicating and constructing
- bisecting
- solving problems.
![Picture](/uploads/2/6/2/1/26215381/398530240.gif)
Things You Need to Know
- Angles are formed between two rays (lines) that meet at a point called the vertex.
- Angles are measured in degrees.
- Complimentary angles are two angles that have measures that add up to 90°.
- A way to remember this: 90° looks like someone sitting perfectly upright. They deserve a compliment for sitting so upright. (That was awful, I'm sorry)
- Supplementary angles are two angles that have measures that add up to 180°.
- A way to remember this: 180° looks like a straight line with the vertex in the middle. Vitamin supplements are also straight lines. (Yikes, that was even worse than the last one)
- On a compass, there are four "cardinal directions": north, east, south, west.
- All the other directions are called "intercardinal directions", like NW, SE, SSW, etc.
- The intercardinal directions with three letters are sometimes tricky to remember. Just remember that if it is something like WSW, that it means it is between west and southwest.
- Directions can be accurately reported using angles. This is called "true bearing". Due north is 0°, and the angles increase as you move clockwise around the compass.
- East is 90°, South is 180°, West is 270°. You'll need to remember these at least.
- If North is 0° and East is 90°, Northeast is right in between them. 90 / 2 = 45°. So the true bearing of NE is 45°.
- NNE is between North and NE. So its true bearing is right in between 0° and 45°. 45 / 2 = 27.5°. So the true bearing of NNE is 27.5°.
- To find the others, just add 45° or 27.5° to the direction before it. So, SSW would be 27.5° more than S. So take 180° and add 27.5° to get 207.5°. So the true bearing of SSW is 207.5°.
- An angle bisector is a line that divides an angle directly in half.
- If you bisected a 64° angle, the bisected angle would be 64 / 2 = 32°.
Interactive Activities
Sample Problems
Class Notes