Measuring & Comparing Angles Angles are measured using a protractor.

Measuring & Comparing Angles Angles are measured using a protractor. They are also measured in degrees. Use the degree symbol… for example, 20°

Measuring & Comparing Angles Vertex Bottom Ray When measuring using a protractor, you must get the vertex and the bottom ray of the angle centered on the zero line of the protractor.

Measuring & Comparing Angles Then read the angle measure by finding where the ray that opens up from the bottom ray lies.

Measuring & Comparing Angles 60° Then read the angle measure by finding where the ray that opens up from the bottom ray lies. In this case, the angle is 60°.

Measuring & Comparing Angles You use the inside scale because the angle is opening up from the right side and the values are increasing as the ray opens up.

Measuring & Comparing Angles Try one…what is the measure of this angle ? Vertex Bottom Ray

Measuring & Comparing Angles Try one…what is the measure of this angle ? Answer : 100°

Measuring & Comparing Angles Try another…what is the measure of this angle ?

Measuring & Comparing Angles Try another…what is the measure of this angle ? Answer : 35° ( use the outside scale since the angle opens up from the left )

Measuring & Comparing Angles Last one…what is the measure of this angle ?

Measuring & Comparing Angles Last one…what is the measure of this angle ? Answer : °58 ( extend the rays if you need to … )

Measuring & Comparing Angles Let’s sketch a few angles…

Measuring & Comparing Angles Let’s sketch a few angles… Draw a 45° angle that opens up from the right.

Measuring & Comparing Angles Let’s sketch a few angles… Draw a 45° angle that opens up from the right. 1. Make a point and center your protractor on it

Measuring & Comparing Angles Let’s sketch a few angles… Draw a 45° angle that opens up from the right. Make a point and center your protractor on it Now use the edge of your protractor and extend the bottom line

Measuring & Comparing Angles Let’s sketch a few angles… Draw a 45° angle that opens up from the right. Make a point and center your protractor on it Now use the edge of your protractor and extend the bottom line Find your angle value on the inside scale ( opens from right ) and place a little hash mark on the outside of the protractor

Measuring & Comparing Angles Let’s sketch a few angles… Draw a 45° angle that opens up from the right. Make a point and center your protractor on it Now use the edge of your protractor and extend the bottom line Find your angle value on the inside scale ( opens from right ) and place a little hash mark on the outside of the protractor Now rotate the bottom edge of the protractor to that hash mark from the vertex and connect the two with a line

Measuring & Comparing Angles Let’s sketch a few angles… Draw a 100° angle that opens up from the left.

Measuring & Comparing Angles Let’s sketch a few angles… Draw a 100° angle that opens up from the left.

Measuring & Comparing Angles Let’s sketch a few angles… Draw a 100° angle that opens up from the left. Make a point and center your protractor on it

Measuring & Comparing Angles Let’s sketch a few angles… Draw a 100° angle that opens up from the left. Make a point and center your protractor on it Now use the edge of your protractor and extend the bottom line

Measuring & Comparing Angles Let’s sketch a few angles… Draw a 100° angle that opens up from the left. Make a point and center your protractor on it Now use the edge of your protractor and extend the bottom line Find your angle value on the outside scale ( opens from left ) and place a little hash mark on the outside of the protractor

Measuring & Comparing Angles Make a point and center your protractor on it Now use the edge of your protractor and extend the bottom line Find your angle value on the outside scale ( opens from left ) and place a little hash mark on the outside of the protractor Now rotate the bottom edge of the protractor to that hash mark from the vertex and connect the two with a line