Today in Geometry we started a new unit with an investigation into the sum of the angles of a polygon based on its number of sides. We quickly previewed what this unit is about. Short version: there will be a test of about 70 points before spring break (just before) but we will finish more algebra after spring break, more proof, unit circle, and then a big quiz over that.

Today we used the investigation and some animation and software driven demonstrations of exterior angles in order to come up with Conjectures 30-34 on pp 256-261.

The sum of the angles of a polygon with n sides is 180(n-2).

The sum of a set of exterior angles of a polygon is 360 degrees.

The angles in a quadrilateral sum to 360 degrees.

The measure of one angle in an equiangular polygon is

180(n-2)/n. OR 180-(360/n).

Every exterior angle is a linear pair to an interior angle. we also defined exterior angle as an angle formed by a side of a polygon and an extension of a side of a polygon.

mathopenref.com was helpful. Choose Geometry, polygons, exterior angle.

Tests were only viewed in 6th period.

HW #14: p 257-8:1-11, p262:1-11. Show arithmetic when looking for missing angles. Copy charts on 1-2. If solving with algebra, show work.

Today we used the investigation and some animation and software driven demonstrations of exterior angles in order to come up with Conjectures 30-34 on pp 256-261.

The sum of the angles of a polygon with n sides is 180(n-2).

The sum of a set of exterior angles of a polygon is 360 degrees.

The angles in a quadrilateral sum to 360 degrees.

The measure of one angle in an equiangular polygon is

180(n-2)/n. OR 180-(360/n).

Every exterior angle is a linear pair to an interior angle. we also defined exterior angle as an angle formed by a side of a polygon and an extension of a side of a polygon.

mathopenref.com was helpful. Choose Geometry, polygons, exterior angle.

Tests were only viewed in 6th period.

HW #14: p 257-8:1-11, p262:1-11. Show arithmetic when looking for missing angles. Copy charts on 1-2. If solving with algebra, show work.