Area and perimeter of triangles

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Lesson Plan · Guided Notes · Exit Ticket · Re-teach · Homework

Lesson Plan →Objectives, pacing and practice, built from this lesson's brief.
Guided Notes →One page your students fill in and keep.
Exit Ticket →Three items at the end of class. No student accounts.
Re-teach →After an exit ticket: who missed what, and what to do tomorrow.
Homework →Assign practice; it grades itself.

G 403. Compute the area and perimeter of triangles and rectangles in simple problems G 506. Compute the area of triangles and rectangles when one or more additional simple steps are required G 302. Compute the perimeter of polygons when all side lengths are given

G 403. Compute the area and perimeter of triangles and rectangles in simple problems
G 506. Compute the area of triangles and rectangles when one or more additional simple steps are required
G 302. Compute the perimeter of polygons when all side lengths are given

What you'll learn

Compute the perimeter of any triangle given its three side lengths
Apply the area formula A = 1/2 * base * height to right triangles and general triangles, correctly identifying the perpendicular height
Find the height of a triangle using the Pythagorean theorem when the height is not directly provided (e.g., in isosceles or equilateral triangles)
Use the equilateral triangle shortcuts: h = ssqrt3/2 and A = s^2sqrt3/4
Compute the area of a triangle from vertex coordinates using the shoelace formula or rectangle-decomposition method

Review first:

Slides

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Triangle area perimeter

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Practice

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Exercise

Practice problems, checked as you go

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