On a map with a scale of 1:4, the bottom of a triangle is 2 cm and the height is 1.5 cm. The actual area of the triangle is ()

On a map with a scale of 1:4, the bottom of a triangle is 2 cm and the height is 1.5 cm. The actual area of the triangle is ()

Length 2 * 4 = 8, width 1.5 * 4 = 6, area 8 * 6 / 2 = 24

Cut an equilateral triangle (one side of the equilateral triangle is the width of the rectangle) from a rectangular iron plate with a circumference of 13 cm
If the width of the rectangle is____ Cm_____ Cm. The remaining area is the largest. The largest area is_____ square centimetre.

Let the width of the rectangle be xcm and the length be (13-2x) / 2cm. X [(13-2x) / 2] - 1 / 2x multiplied by (root 3 / 2) x = (- 4x ^ 2 + 26x) / 4 - (root 3 / 4) x ^ 2 = - 1 / 4 (4 + root 3) {[x ^ 2-2 (4 + root 3) x + (4 + root 3) ^ 2] - (4 + root 3) ^ 2} = - 1 / 4 (4 + root 3) [x - ()] ^ 2 + 25 + (51 times root 3) / 4

If an equilateral triangle (one side of the equilateral triangle is the width of the rectangle) is cut off from a rectangular iron plate with a circumference of 13cm, the width of the rectangle is___ Cm in length___ Cm, the remaining area is the largest___ ．

Let the width of the rectangle be x and the length be (132-x), then the area left after the triangle is cut out is (132-x) x-12x · 32x. After sorting, it is concluded that y = - 4 + 34x2 + 132x. When x = - B2A = 4-3, y has the maximum value, y max = 134 (4-3), and the length is (52 + 3)