Unit 7, Lesson 12
Radian Sense
Geometry
12.1
Warm-up
Which Three Go Together: Angle Measures
Which three go together? Why do they go together?
A
B
C
D
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Which three go together? Why do they go together?
A
B
C
D
This double number line shows measures in degrees on one line and in radians on another.
30
120
Your teacher will give you a set of cards with angle measures on them. Place the cards upside down in a pile. Take turns with your partner drawing a card.
| card | measure in radians (may be blank) | total shaded, in radians |
|---|---|---|
| card | measure in radians (may be blank) | total shaded, in radians |
|---|---|---|
When you’re finished, answer these questions about each circle:
We can divide circles into congruent sectors to get a sense for the size of an angle measured in radians.
Suppose we want to draw an angle that measures
Another way to understand the size of an angle measured in radians is to create a double number line with degrees on one line and radians on the other. On the double number line shown here, the degree measures are aligned with their equivalent radian measures. For example,
Suppose we need to know the size of an angle that measures