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This educational content explores the concept of triangle area, providing clear definitions, formulas, and step-by-step examples for calculating the area of various triangles. It explains how area is measured using square units and includes formulas like A = ½bh for different types of triangles, including right and obtuse triangles. Specific examples include calculating the area given base and height measurements in both inches and centimeters. Additionally, the material helps identify relationships within triangles, ensuring a comprehensive understanding of triangle area calculations.
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Area of triangles Unit 5
Getting the idea • Area is a measure of the number of square units needed to cover a region. • Square Unit is a square with a side length of 1 of any particular unit of measure. • Square Inches = in2 • Square Centimeters = cm2
Formula for area of a triangle. • Area equals one-half the base (b) times the height (h). • A = ½bh h b h b
1. What is the area of the triangle? • Step One: Determine the formula for the area of a triangle. • A = ½ bh • Step Two:Substitute the values for the baseand the height into the formula. • The base, b, measures 8 inches and the height, h, measures 4 inches. • A = ½ (8)(4) • Step Three: Multiply • A = ½ (8)(4) • A = ½ (32) = ● = • A = *divide by 2* • A = 16 • Step Four: Write the answer with correct unit of measure squared. • Area = 16 in2 4 in 8 in
Right Triangle • Remember that a right triangle has a hypotenuse and 2 sides called legs. • The legs form a right angle. • To find the area of a right triangle, use the legs as the base and height. Hypotenuse
2. What is the area of the triangle? • Step One: Determine the formula for the area of a triangle. • A = ½ bh • Step Two:Substitute the values for the base and the heightinto the formula. • The base, b, measures 9 cm and the height, h, measures 3 cm. • A = ½ (9)(3) • Step Three: Multiply • A = ½(9)(3) • A = ½ (27) = ● = • A = *divide by 2* • A = 13.5 • Step Four: Write the answer with correct unit of measure squared. • Area = 13.5 cm2 3 cm 9 cm
In an obtuse triangle, you can extend a side to find the height. Obtuse Angle: Angle greater than 90˚
3. What is the area of the triangle? • Step One: Determine the formula for the area of a triangle. • A = ½ bh • Step Two:Substitute the values for the base and the height into the formula. • The base, b, measures 12 feet and the height, h, measures 5 feet. • A = ½ (12)(5) • Step Three: Multiply • A = ½(12)(5) • A = ½ (60) = ● = • A = *divide by 2* • A = 30 • Step Four: Write the answer with correct unit of measure squared. • Area = 30 ft2 5 ft 12 ft
4. What is the height of a triangle with an area of 40m2and a base of 10 m? • Step One:Determine the formula for the area of a triangle. • A = ½ bh • Step Two:Substitute the values for the areaand the base into the formula. • The Area , A, is 40 m2 and the base, b, measures 10 m. • 40 = ½ (10)(h) • Step Three: Solve the Equation • 40 = ½ (10)(h) = ● (h) = (h) = 5h • 40 = 5h *divide both sides of equal sign by 5 (isolate the variable) • 8= h • Step Four: Write the answer with correct unit of measure. • height = 8 m
5. The Clarke family built a triangular deck at the back of their house. What Is the area of the triangular deck if the base is 9 yards and the height is 7 yards? • Draw the triangular deck and label the base and the height. • Write the formula for finding the area of a triangle. • Substitute the base and height into the formula. • Solve the formula to determine the area of the triangular deck.
6. A triangular pennant has a base that is 18 inches long and a height of 6 ½ inches. What is the area of the pennant? • Draw the triangular pennant and label the base and the height. • Write the formula for finding the area of a triangle. • Substitute the base and height into the formula. • Solve the formula to determine the area of the triangular pennant.
7. The Area of a triangle is 30 yd2 and its height is 6 yd. What is the length of the base? • Write the formula for finding the area of a triangle. • Substitute the Area and height into the formula. • Solve the formula to determine the base of the triangle.
8. Mr. Butler drew these two triangles on the board: 34 in 34 in • 1. What is the area of Triangle A? • 2. What is the area of Triangle B? • 3. Describe what you notice about the two triangles. 18 in 26 in 30 in 30 in Triangle A 26 in Triangle B