Area of Parallelograms Triangles Grade 7 Math Background

Area of Parallelograms & Triangles Grade 7 Math

Background Vocabulary • Parallel lines are lines that run side by side that will NEVER intersect. They’re often marked with little matching arrows to show they are the same. • Perpendicular lines are lines that intersect AND they make 90 degree angles where they intersect • Not all intersecting lines are perpendicular

Background Vocabulary • Parallel lines • Perpendicular lines • Intersecting lines • Line segments can be labelled

What is a PARALLELOGRAM? Parallelograms are 4 sided shapes. The opposite sides are parallel to each other. They are not always straight up and down sides (that make 90 degree angles) like squares or rectangles though. See how 3 of these parallelograms look like they are tilted.

Length vs. Height - What’s the diff? • Have you ever learned that the area of a rectangle was length x height? • Yes, that does work • Unfortunately you CAN’T use that formula for many other parallelograms. • However, you can use THIS formula for ALL parallelograms (including squares and rectangles): A = bh (Area = base x height)

Practice: Finding the area of a parallelogram

How do you use the AREA of a Parallelogram to find the base or height? • Sometimes you’ll be given the area of a parallelogram and will be asked to find the height. • For example. Cher has enough parallelogram-shaped tiles to cover a section of wall with an area of 840 cm(squared). The design will have a base of 12 cm. How high can Cher make his design? • Use the same formula for area to start: A = bh *in this problem we are finding h. H is the unknown but we know the A (area) and we know the b (base).

How do you use the AREA of a Parallelogram to find the base or height? • Sometimes you’ll be given the area of a parallelogram and will be asked to find the base. • For example. Loudette is making a fancy parallelogram-shaped cake for my birthday. The total area of cake needed for the class is 1200 cm squared. The cake has a height of 30 cm. How long will the base be? • Use the same formula for area to start: A = bh *in this problem we are finding b. b is the unknown but we know the A (area) and we know the h (height).

Practice for you! • IXL (remember I sent you an email with your log-in info a few weeks ago) • Two Dimensional Figures: W. 10 Parallel, Perpendicular, Intersecting Lines • Geometric Measure: AA. 2 Areas of Rectangles & Parallelograms • Mathletics: • Shape - Area: Parallelograms

Some problems you might encounter in IXL …