Angles of Triangles

Notes-watch videos on “Third Angle Theorem”, and “Exterior Angle Theorem” OR Notes from section 4-2 Pages Define exterior angle, and remote interior angle Write and draw diagrams for: Angle Sum Theorem Third Angle Theorem Theorem (just the drawings and the Example) Exterior Angle Theorem Corollary 4.1 (in box on page 213) Title your notes and examples “Angles of Triangles” and add the date and your name Notes should be used on assignments and should be left in folder.

Assignment 1- interior angles Using half of a sheet of paper, draw a large triangle (use a ruler!) Measure the angles of the triangle using the protractor Label the measures inside each angle. Cut out the triangle. Take a pair of scissors, and cut off all three triangles of each angle On a sheet of construction paper, arrange all three angles into a straight line, and glue them down. Using a marker, write on the construction paper: “The interior angles of a triangle add up to 180 °”.

Assignment 2- exterior angles On the other half of your sheet, draw a large triangle Label the vertices A, B, and C Cut out angles A and B Arrange Angle A and B next to Angle C so that the three angles form a straight line. Glue the angles to the other side of your construction paper. Using a marker, write “ two angles of a triangle make a straight line with the third angle of the triangle.”

Khan Assignment Go to Khanacademy.org and complete these skills: Triangle Angles 1 Finding Angle Measures 1

Essential Questions If we know two angles of a triangle, how can we find the third angle? If we have an isosceles triangle, and only know 1 angle, how can we find the other two angles? If we have an equilateral triangle, do we ever have to compute or measure the angles of the triangle? Why or why not?

Leave all work in folder.