Answer:

Step-by-step explanation:
The complete question in the attached figure
we know that
The surface area of a cube is equal to the area of its 6 squares faces
so
The area of one square face is equal to

where
b is the length side of the square
we have

substitute
---> area of one square face
Find the surface area of three cubes
Multiply the area of one square face by 6 (one cube has 6 faces) and then multiply the result by 3 (3 cubes)
so
![SA=3[6(1)]=18\ ft^2](https://tex.z-dn.net/?f=SA%3D3%5B6%281%29%5D%3D18%5C%20ft%5E2)
No, it will not be able to make a right triangle.
<em><u>Solution:</u></em>
Given that,
Joel wants to fence off a triangular portion of his yard for his chickens.
The length of three peices of fencing are 8 feet , 15 feet and 20 feet
For making it a right triangle it must satisfy the "Pythagorus theorem"
Pythagorean theorem, states that the square of the length of the hypotenuse is equal to the sum of squares of the lengths of other two sides of the right-angled triangle.
For a right angled triangle with sides a, b, c

Given sides are:
a = 8 feet
b = 15 feet
c = 20 feet
Substituting the values in above formula

Since the pythogoras formula is not satisfied, the given sides cannot form a right angled triangle
Thus , No, it will not be able to make a right triangle.
The human ran at about 0.45 of a mile per minute
The given lines are perpendicular to each other.
Further explanation:
Given lines are:
Line 1: y= -9/5x + 1/5
Line 2: y= 5/9x + 2/9
As the lines are in slope=intercept form, the co-efficient of x are their slopes
Let m1 be the slope of line 1 and m2 be the slope of line 2
Then

As we can see that the product of slopes of both lines is -1. The product of slopes of perpendicular lines is -1.
The given lines are perpendicular to each other.
Keywords: Slope, slope-intercept form
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