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monitta
2 years ago
15

If the radius of a coin is 20cm ,find its surface area.​

Mathematics
1 answer:
jasenka [17]2 years ago
4 0

Answer:

It's surface area is 1257.14cm^2

Step-by-step explanation:

area=22/7×20cm×20cm

=3.14×20cm×20cm

=1257.14cm^2

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3h - j when h = 8 and j = 11<br> plzzz help
AURORKA [14]

Answer:

13

Step-by-step explanation:

3h - j

3(8) - 11

24 - 11

13

8 0
2 years ago
Iv)<br>6x+3y=6xy<br>2x + 4y= 5xy​
Margaret [11]

Answer:

Ok, we have a system of equations:

6*x + 3*y = 6*x*y

2*x + 4*y = 5*x*y

First, we want to isolate one of the variables,

As we have almost the same expression (x*y) in the right side of both equations, we can see the quotient between the two equations:

(6*x + 3*y)/(2*x + 4*y) = 6/5

now we isolate one off the variables:

6*x + 3*y = (6/5)*(2*x + 4*y) =  (12/5)*x + (24/5)*y

x*(6 - 12/5) = y*(24/5  - 3)

x = y*(24/5 - 3)/(6 - 12/5) = 0.5*y

Now we can replace it in the first equation:

6*x + 3*y = 6*x*y

6*(0.5*y) + 3*y = 6*(0.5*y)*y

3*y + 3*y = 3*y^2

3*y^2 - 6*y = 0

Now we can find the solutions of that quadratic equation as:

y = \frac{6 +- \sqrt{(-6)^2 - 4*3*0} }{2*3} = \frac{6 +- 6}{6}

So we have two solutions

y = 0

y = 2.

Suppose that we select the solution y = 0

Then, using one of the equations we can find the value of x:

2*x + 4*0 = 5*x*0

2*x = 0

x = 0

(0, 0) is a solution

if we select the other solution, y = 2.

2*x + 4*2 = 5*x*2

2*x + 8 = 10*x

8 = (10 - 2)*x = 8x

x = 1.

(1, 2) is other solution

8 0
2 years ago
the ratio of pink marbles to white marbles in Samaras bag is equal to 1:5. what percent of the bag contains pink marble
kenny6666 [7]
1:5= 1/5 x 20/20= 20/100

20/100= 0.20

The bag contains 20% of pink marbles.
3 0
3 years ago
Please help me with 3.2 ​
Lady_Fox [76]

The measure of the angle ∠PQR is 90 degrees

<h3>How to prove that ∠PQR is 90 degrees?</h3>

The equation of the line PQ is given as:

3x - y - 2 = 0

The coordinates of the QR are given as:

(0, -2) and (6, -4)

Make y the subject in 3x - y - 2 = 0

y = 3x - 2

The slope of the above line is

m1 = 3

Next, we calculate the slope (m2) of points Q and R.

So, we have:

m2 = (y2- y1)/(x2 - x1)

This gives

m2 = (-4 + 2)/(6 - 0)

Evaluate

m2 = -1/3

The slopes of perpendicular lines are opposite reciprocals.

m1 = 3 and m2 = -1/3 are opposite reciprocals.

This means the lines PQ and QR are perpendicular lines.

The angle at the point of perpendicularity is 90 degrees

Hence, the measure of the angle ∠PQR is 90 degrees

Read more about linear equations at:

brainly.com/question/15602982

#SPJ1

4 0
2 years ago
Ill give brainliest
yuradex [85]

Answer:

y-coordinate is 5 or -1.

Step-by-step explanation:

Point A is at (x, 2) and B is at (x+6, 2). Since AB must lie on the line y=2  and be 6 units long. Point C is on the line x = -3 . So let C be at (-3, y).

Since ΔABC is a right angle, then point C must have the same x-coordinate as point A. Therefore, A(-3, 2) and B(2, 2).

The area of ΔABC is 6. So,

9 = 1/2 (b)(h)

where b is the base and h is the height.

so b = 6 and h = AC

Solving this for C gives

9 = 1/2 (6)(AC)

18/6 = AC

3 = AC

9 = 1/2 (6)(AC)

18/6 = AC

3 = AC

Point C must lie 3 units above point A or 3 units below the point A. If it lies 3 units above, then it has a y-coordinate of 2 + 3 = 5.

If it lies 3 units below, it has a y-coordinate 2 - 3 = -1.

Therefore, y-coordinate is 5 or -1.

Step-by-step explanation:

5 0
3 years ago
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