Answer:
Triangles have been used extensively throughout history in construction due to their rigid shape and strength. Unlike a square, that can shift into a parallelogram when force is applied to one of its sides, an equilateral triangle's sides and angles are fixed.
Due to the rigidness of the triangle's shapes, high amounts of forces can be sustained without deformation. Triangles are often used as trusses in bridges, or other support structures in buildings. They can easily be fit together to provide strength and stability over a wide area. The most famous triangles in structures are the pyramids of Egypt, which are the largest pyramids in the world.
Step-by-step explanation:
Triangles are used in structures because a triangle is a very stable shape that cannot be stretched or squashed easily - unlike rectangles which can easily become parallelograms. It's angles are used to balance weight of any structure.
6,200
Take 12 and multiply it by 350 to get 4,200 then add 2,000 to get 6,200
Answer:
7. 
8. l=11cm and w=7 cm
9. 
10. 
Step-by-step explanation:
Question 7.
The given expression is:

Expand the parenthesis using the distributive property:

Group similar terms:

Simplify

Divide both sides by -10

Question 8:
Let the width of the rectangle be;
The length of the rectangle is 
The perimeter is given as: 
Given that the perimeter P=36, then:
![36=2[(w+4)+w)]](https://tex.z-dn.net/?f=36%3D2%5B%28w%2B4%29%2Bw%29%5D)

Divide both sides by 2:

Subtract 4 from both sides:



The dimensions of the rectangle is: w=7 cm and l=7+4=11cm
Question 9
Let the number be x.
"5 fewer than the number" is written as 
"5 fewer than a number is at least 12" becomes

Question 10:
Let the number be x.
The quotient of a number and 3 is written as:

The quotient of a number and 3 is no more than 15 is written as;

One piece cause half of 8 is 4 and there is 3 people
width = w
length = w+4
Area = l*w
substitute
96 = (w+4) *w
distribute
96 = w^2 +4w
subtract 96 from both sides
0 = w^2 +4w -96
factor
0=(w+12) (w-8)
w+12=0 w-8=0
w=-12 w=8
cannot have negative width
w=8
l=12
Answer: width =8 cm
length = 12cm