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5.2 Area of Triangles, Parallelograms, & Trapezoids. Objectives: Develop & apply formulas for the area of triangles, parallelograms, & trapezoids. Warm-Up:. The length of the rectangle is 4 inches less than 3 times the width. The perimeter is 40 inches. Find the length and the width.
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5.2 Area of Triangles, Parallelograms, & Trapezoids Objectives: Develop & apply formulas for the area of triangles, parallelograms, & trapezoids. Warm-Up: The length of the rectangle is 4 inches less than 3 times the width. The perimeter is 40 inches. Find the length and the width.
Collins Writing: Draw a right triangle, how do you think we could determine the area if we only knew the length of the legs? ________________________________ ________________________________ ________________________________ 3 lines 2 minutes
Parts of a Triangle: • Base: Any side of a triangle • Note-for each possible choice of the base of a triangle, there is a corresponding altitude and height • Altitude: a perpendicular segment from a vertex • to a line containing the base of the triangle. • Height: the length of the altitude • altitude • base
The area of a triangle can be found by multiplying the base by one half of the height(altitude) Note: the height must be PERPENDICULAR to the BASE!!! Area =
35in 29in 21in 48in Area = ? Area = ?
The base of one of the triangles in the pinwheel is 4 cm, the area is 14 cm2, what is the height of one triangle?
Parts of a Parallelogram: • Base: Any side of a parallelogram • Altitude: a perpendicular segment from a line containing the base to a line containing the side opposite the base. • Height: the length of the altitude • base • altitude • base
Parts of a Trapezoid: • Bases: the two parallel sides of a trapezoid • Legs: the two non-parallel sides of a trapezoid • Altitude: a perpendicular segment from a line containing one base to a line containing the other base. • Height: the length of the altitude • base • altitude • base
Example: • Use the diagram and measurements given below to find the areas of the indicated figures. • ∆VWZ = ______ • 9 • W • X • ∆WXY = ______ • 10 • 17 • 8 • VWXY = ______ • Z • Y • 6 • V • WXYz = ______
B A C 2 HSPA questions of the day: ABC is an isosceles triangle. AB BC and m<ABC = BAC = A. 26o B. 64o C. 77o D. 154o m<2 = A. 26o B. 154o C. 72o D. 103o
Homework: • Pages 308-309; Numbers 10-30