The perimeter of the rectangle is 20\text{ cm}20 cm20, start text, space, c, m, end text. One side is 6\,\text{cm}6cm6, start text, c, m, end text long. What is the length of the missing side?

The lenght of the missing side is 4 cm

Step-by-step explanation:

The correct question is:

The perimeter of the rectangle is 20cm . One side is 6cm. What is the length of the missing side?

So, to answer it we have to apply the next formula:

Perimeter of a rectangle = 2 width + 2 length

Replacing with the values given: (assuming that the side given is the length of the rectangle)

20 = 2(6) + 2x

Solving for x:

20 =12 +2x

20-12 =2x

8 =2x

8/2 =x

4=x

The length of the missing side is 4 cm

Feel free to ask for more if needed or if you did not understand something.  

your answer would be 12

the arc length is found by finding the circumference of the full circle (2xpixradius) and then dividing by 4 to find just one quarter of the circle (90 degrees).