A school plans to plant turf on a triangular open space. If it is known that this kind of turf costs a yuan per square meter, it needs at least () A. 450A yuan b.225a yuan c.150a yuan d.300a yuan Triangle ABC, ab = 20m, AC = 30m,

A school plans to plant turf on a triangular open space. If it is known that this kind of turf costs a yuan per square meter, it needs at least () A. 450A yuan b.225a yuan c.150a yuan d.300a yuan Triangle ABC, ab = 20m, AC = 30m,

Extend Ca, make BD perpendicular to Ca and intersect point D
Because the triangle area s = 1 / 2bd * AC = 1 / 2 * 10 * 30 = 150 square meters
The money needed is 150A yuan

There is a triangular land with three sides of 13, 14 and 15 meters long. It costs 120 yuan per square meter. How much does it cost at least? Thinking about Pythagorean theorem

The height h of a triangle over 15 sides
Then 169-x ^ 2 = 196 - (15-x) ^ 2
The solution is x = 6.6
h=11.2
S=0.5*15*11.2=84

Lay a 2-meter wide lawn around the square flower bed. The lawn area is 40 square meters. How many square meters does the lawn and flower bed occupy

Side length of square flower bed = (40-2x2x4) △ 4 △ 2 = 3M
The total area of lawn and flower bed is (3 + 2 + 2) x (3 + 2 + 2) = 49 square meters,

A square flower bed should be built in the park, and a 2m wide lawn should be laid beside the flower bed. The lawn area is 96 square meters. What is the total area of flower bed and lawn? If the side length of flower bed is x, then （X+4)^2_ X^2=96 X^2+8X+16-X^2=96 8X=80 X=10 S total = (10 + 4) ^ 2 = 196 square meters

If the side length of a square is x, then:
(x+4)*(x+4)-x*x=96
x=10
10 * 10 + 96 = 196 square meters

In a square flower bed around the spread of 2 meters wide lawn, lawn area is 96 square meters

In a square flower bed around the spread of 2 meters wide lawn, lawn area is 96 square meters
Side length of square:
（96-2×2×4）÷2÷4
=80÷2÷4
=10m
Square area 10 × 10 = 100 square meters

Lay a 2-meter wide lawn around the square flower bed. The total area of the lawn is 40 square meters. How many square meters does the lawn and flower bed occupy?

Divide the lawn into 4 parts, each area: 40 ￣ 4 = 10 (square meters) each length: 10 ￣ 2 = 5 (meters) the length of the big square: 5 + 2 = 7 (meters) the area of the big square: 7 × 7 = 49 (square meters) answer: the total area is 49 square meters

Build a square flower bed and spread a 4-meter wide lawn around the flower bed. The lawn area is 108 square meters. What is the total area of the lawn and flower bed

Let X be the side length of flower bed, then the square of (x + 8) minus the square of X is equal to 108

There is a circular flower bed in the park, with a diameter of 16 meters. A 2-meter-wide circular access road is built around it. What is the area of this access road? (the value of PI is taken as 3) A floor lamp is installed every 5 meters along the outer edge of the circular access road. How many floor lamps should be installed?

The area of this access road is:
3×[﹙16／2﹢2﹚²-﹙16／2﹚²]
=3×36
=108 (square decimeter)

There is a circular flower bed with a diameter of 16m, and a 2m wide path is built around it (1) What is the area of this path? (2) How many lamps should be installed along the edge of the circular path every 5m?

(1) 16 △ 2 = 8 (m), 8 + 2 = 10 (m),
3×（102-82），
=3×（100-64），
=3×36，
=108 square meters;
A: the area of this path is 108 square meters
（2）3×10×2÷5，
=60÷5，
=12;
A: a total of 12 lamps will be installed

There is a circular flower bed in the park, with a diameter of 16 meters. A 2-meter-wide Circular Road (pi = 3) is built around her. What is the area of the access road 2. A lamp is installed every 5 meters along the ring road. How many lamps should be installed

Inner radius 16 △ 2 = 8M
Outer radius 8 + 2 = 10m
Area 3.14 × (10 × 10-8 × 8)
=3.14×36
=113.04 square meters
3.14×10÷5
=31.4÷5
About 6