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Ch 10.4. Find the perimeter of the figure. Round to the nearest tenth if necessary. 13(2) + 11(2) = 48 cm. Find the perimeter of the figure. Round to the nearest tenth if necessary. 10 + 17.9 + 10 = 37.9 ft.
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Ch 10.4 Find the perimeter of the figure. Round to the nearest tenth if necessary. 13(2) + 11(2) = 48 cm Find the perimeter of the figure. Round to the nearest tenth if necessary. 10 + 17.9 + 10 = 37.9 ft The area of an obtuse triangle is 52.92 square centimeters. The base of the triangle is 12.6 centimeters. What is the height of the triangle? 52.92 = 12.6h h = 8.4 cm 2 5-Minute Check 1
Ch 10.4 Learning Target: I will be able to find the areas of trapezoids. Standard 10.0 Students compute areas of polygons. Ch 10.4(2)Areas of Trapezoids
Ch 10.4 Theorem 10-4 Concept 1
Ch 10.4 Area of a Trapezoid SHAVINGFind the area of steel used to make the side of the razor blade shown below. Area of a trapezoid h = 1, b1 = 3, b2 = 2.5 Simplify. Answer:A = 2.75 cm2 Example 1
Ch 10.4 Find the area of the side of the pool outlined below. A. 288 ft2 B. 295.5 ft2 C. 302.5 ft2 D. 310 ft2 Example 1
Ch 10.4 OPEN ENDEDMiguel designed a deck shaped like the trapezoid shown below. Find the area of the deck. Read the Test Item You are given a trapezoid with one base measuring 4 feet, a height of 9 feet, and a third side measuring 5 feet. To find the area of the trapezoid, first find the measure of the other base. Example 2
Ch 10.4 OPEN ENDEDMiguel designed a deck shaped like the trapezoid shown below. Find the area of the deck. Solve the Test Item Draw a segment to form a right triangle and a rectangle. The triangle has a hypotenuse of 5 feet and legs of ℓ and 4 feet. The rectangle has a length of 4 feet and a width of x feet. Example 2
Ch 10.4 Use the Pythagorean Theorem to find ℓ. a2 + b2 = c2 Pythagorean Theorem 42 + ℓ2 = 52 Substitution 16 + ℓ2 = 25 Simplify. ℓ2 = 9 Subtract 16 from each side. ℓ = 3 Take the positive square root of each side. Example 2
Ch 10.4 By Segment Addition, ℓ + x = 9. So, 3 + x = 9 and x = 6. The width of the rectangle is also the measure of the second base of the trapezoid. Area of a trapezoid Substitution Simplify. Answer: So, the area of the deck is 30 square feet. Example 2
Ch 10.4 The area of the trapezoid is the sum of the areas of the areas of the right triangle and rectangle. The area of the triangle is or 6 square feet. The area of the rectangle is (4)(6) or 24 square feet. So, the area of the trapezoid is 6 + 24 or 30 square feet. Check Example 2
Ch 10.4 Ramon is carpeting a room shaped like the trapezoid shown below. Find the area of the carpet needed. A. 58 ft2 B. 63 ft2 C. 76 ft2 D. 88 ft2 Example 2
Ch 10.4 Trapezoid QRST has an area of 210 square yards. Find the height of QRST. A. 3 yd B. 6 yd C. 2.1 yd D. 7 yd Example 4
Ch 10.4 Concept 3