Class Today

Today we began class by correcting the homework p.519 # 22-49. The problems below are problems that she explained on the board:

38) The number of sides of a regular polygon is given. Find the measures of an interior angle and an exterior angle for each polygon. Round to the nearest hundredth.

n= number of sides

e = (exterior angle)

i = (interior angle)

n=3m

e= =

i = 180 - e = 180 - 120 m = 60 m

45) The measure of an interior angle of a regular polygon is given. Find the number of sides.

i =

i = (because this is the formula to find the number of sides, you know that the s given in the problem actually represents n, or the number of sides that the polygon has. You just have to do the distributive property)

48) If the exterior angle of a regular polygon measures 36, find the sum of the measures of the interior angles.

e=36

Si= 180 (n - 2)

36 (exterior angle) =

n = 10 ( now substitude n with ten in the formula: Si = 180 ( n - 2) and you get the interior angle measurment.)

The Lesson today: Areas and Perimeters of: Squares, Rectangles, and Parrallelograms.

Squares:

P= 4l units

A=

Rectangles:

P = 2l + 2w units

A = lw

Parralelograms:

P = 2b + 2m

A = bh

The red triangle that is part of the parralelogram is congruent to the green triangle outside of the polygon. Without the red triangle and with the green one, the area is still the same, but now can be measured as a rectangle's area, therefore it is the height of the polygon times its base.

The homework she assigned for tomorrow is: p. 532 # 10 - 24 all

*Jenni