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Area of triangles

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 = in 2 Square Centimeters = cm 2. Formula for area of a triangle.

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Area of triangles

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  1. Area of triangles Unit 5

  2. 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

  3. Formula for area of a triangle. • Area equals one-half the base (b) times the height (h). • A = ½bh h b h b

  4. 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

  5. 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

  6. 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

  7. In an obtuse triangle, you can extend a side to find the height. Obtuse Angle: Angle greater than 90˚

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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

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