The video introduces a method to measure angles using radians, contrasting it with arc length. It explains why arc length is not a reliable measure due to its dependence on circle size. The concept of similar pies is introduced, leading to the definition of radian measure as the ratio of arc length to radius. An example is provided to illustrate the calculation of radians, explaining the relationship between radians and radii.

What is one way to think about measuring angles?

• By the height of the arc

• By the weight of the arc

• By the length of the arc it subtends

• By the color of the arc

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Why can't we use arc length alone to measure angles?

• Because it depends on the size of the circle

• Because it depends on the weight of the circle

• Because it depends on the color of the circle

• Because it depends on the height of the circle

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What does it mean for two pies to be similar?

• They have the same color

• They have the same height

• They have the same weight

• They can be mapped onto each other through dilations

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What is the radian measure of an angle?

• The ratio of the arc length to the area

• The ratio of the arc length to the circumference

• The ratio of the arc length to the radius

• The ratio of the arc length to the diameter

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How is the circumference of a circle calculated?

• 2 times the radius

• Pi times the diameter

• 2 times Pi times the radius

• Pi times the radius

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In the example, what is the radius of the circle?

• 1 meter

• 2 meters

• 3 meters

• 4 meters

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What is the length of the arc subtended by angle GFH in the example?

• 3 Pi meters

• 2 Pi meters

• 4 Pi meters

• Pi meters

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CCSS.4.MD.C.5B

CCSS.HSG.CO.A.1

What is the measure of angle GFH in radians?

• Pi/2

• Pi

• 3 Pi/2

• 2 Pi

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Why is the term 'radians' used?

• Because it sounds like 'area'

• Because it sounds like 'circumference'

• Because it sounds like 'diameter'

• Because it sounds like 'radius'

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What does dividing the arc length by the radius tell us?

• The number of diameters equivalent to the arc length

• The number of circumferences equivalent to the arc length

• The number of areas equivalent to the arc length

• The number of radii equivalent to the arc length

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CCSS.4.MD.C.5B

CCSS.HSG.CO.A.1