Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Tham khảo tài liệu 'math word problem demystified phần 9', ngoại ngữ, anh ngữ phổ thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | LESSON 20 Word Problems in Geometry X 36 2x 2 36 72 Hence the measures of each of the angles are 36 72 and 72 . EVALUATION See if the sum of the angles is 180 . 36 72 72 180 EXAMPLE If the length of a rectangle is four times its width and the perimeter of the rectangle is 80 inches find the measures of its length and width. Geometric principle The perimeter of a rectangle is p 21 2w. SOLUTION GOAL You are being asked to find the length and width of a rectangle. STRATEGY Let X the width of the rectangle and 4x the length of the rectangle See Figure 20-2. 4x X X 4x Fig. 20-2. Since the formula for the perimeter of a rectangle is p 2ỉ 2w the equation is 2 4x 2x 80. LESSON 20 Word Problems in Geometry IMPLEMENTATION Solve the equation 2 4x 2x 80 8x 2x 80 10x 80 Tơ _ 80 X 8 4x 4 8 32 Hence the length is 32 inches and the width is 8 inches. EVALUATION Use the formula for perimeter and see if it is 80 inches. p 2 2w p 2 32 2 8 64 16 80 inches EXAMPLE The base of a triangle is 6 inches larger than its height. If the area of the triangle is 8 square inches find the base and height of the triangle. Geometric principle . The area of a triangle is A bh. SOLUTION GOAL You are being asked to find the measures of the base and the height. STRATEGY Let X the measure of the height and X 6 the measure of the base LESSON 20 Word Problems in Geometry Fig. 20-3. See Figure 20-3. since A hh the equation is18 x 6 x. IMPLEMENTATION Solve the equation 8 i x 6 x 2-8 2 x x 6 16 x x 6 16 X2 6x 16 16 X2 6x 16 0 X2 6x 16 0 x 8 x 2 X 8 0 x 8 8 0 8 X 8 X 2 0 . V - 2 2 0 2 In this case we ignore x 8 since a height cannot be a negative number. The base is x 6 2 6 8 inches. Hence the height is 2 inches and the base is 8 .