Areas of Triangles, Trapezoids, and RhombiSection 11.2

Areas of Triangles, Trapezoids, and Rhombi•How do I find the areas of triangles?•How do I find the areas of trapezoids and

rhombi?

Area of a Triangle

•Area =

•Height is from a vertex, perpendicular to the opposite side.

•This opposite side is the base.

Triangle Example

•Find the area

Area of a Trapezoid

•Area =

•Height has the same rules as the triangle

Trapezoid Example

•Find the area

Area of a Rhombus

•Remember a rhombus has 4 equal sides

•We use diagonals to find the area

•Area =

Rhombus Example

•Find the area

Example

•Find the area of quadrilateral ABCD if AC = 35, BF = 18, and DE = 10.

Coordinate Plane Example

•Find the area of trapezoid RSTU with vertices R(4, 2), S(6, -1), T(-2, -1), and U(-1, 2).

Coordinate Plane Example

•Find the area of rhombus MNPR with vertices at M(0, 1), N(4, 2), P(3, -2), and R(-1, -3).

Example

•Rhombus RSTU has an area of 64 square inches. Find US if RT = 8 inches.

Example

•Trapezoid DEFG has an area of 120 square feet. Find the height of DEFG.

Your Turn1. Find the area of quadrilateral HIJK if IK = 16, HL = 5, and JM = 9.

2. Find the area of trapezoid WXYZ with vertices W(-3, 0), X(1, 0), Y(2, -3), and Z(-5, -3).

3. Trapezoid QRST has an area of 210 square yards. Find the height of QRST.

Homework

•Page 606▫16 - 20 Even▫30 – 34 Even▫40 – 44 Even

Lesson Plan• Intro

▫Adding area of triangles, trapezoids and rhombi• Standards- 10.2• Supplies – slides, whiteboard, note sheets • Timing: One day for notes, one day for a combined

review of 10.1 and 10.2 followed by a quiz• Day 1:

▫Essential Questions- slides 2▫ Input-slides 3, 5, 7▫Guided Practice - slides 4, 6, 8 - 14▫ Independent Practice – bookwork