IM 7.7.2 Lesson: Adjacent Angles
Estimate the degree measure of each indicated angle.
You are given the following two applets,
- In one of the applets, drag the red point to draw a small half-circle in the middle of one side.
Cut a straight line, starting from the center of the half-circle, all the way across the paper to make 2 separate pieces. (Your cut does not need to be perpendicular to the side of the paper.)
- On each of these two pieces, measure the angle that is marked by part of a circle. Label the angle measure on the piece.
Clare measured 70 degrees on one of her pieces. Predict the angle measure of her other piece.
In the other app,
- Draw a small quarter-circle in one of the corners.
- Repeat the previous steps to cut, measure, and label the two angles marked by part of a circle.
Priya measured 53 degrees on one of her pieces. Predict the angle measure of her other piece.
Use the protractor in the picture to find the measure of angles and .
Explain how to find the measure of angle without repositioning the protractor.
Use the protractor in the picture to find the measure of angles and .
Explain how to find the measure of angle without repositioning the protractor.
Angle is a right angle. Find the measure of angle .
Point is on line . Find the measure of angle .
Clare started with a rectangular piece of paper. She folded up one corner, and then folded up the other corner, as shown in the photos.
- Try this yourself with any rectangular paper. Fold the left corner up at any angle, and then fold the right corner up so that the edges of the paper meet.
- Clare thought that the angle at the bottom looked like a 90 degree angle. Does yours also look like it is 90 degrees?
- Can you explain why the bottom angle always has to be 90 degrees? Hint: the third photo shows Clare’s paper, unfolded. The crease marks have dashed lines, and the line where the two paper edges met have a solid line. Mark these on your own paper as well.