# computing areas and perimeters of simple figures and other stuff

• Aug 28th 2009, 06:43 AM
student897
computing areas and perimeters of simple figures and other stuff
i dont understand these problemss.....please help me on them i got a summer packet and i dont understand almost none of the problemsss(Crying)anyway here are the problems

if the area of a circle is 64pi, then what is the circumfrence?

if the minute hand of a clock moves 45 degrees, how many minutes of time have passed?

a triangle of height 5 and base 4 has an area exactly 1/3 that of a rectangle with height 5 . what is the width of the rectangle?

here are some other problems i dont understand..

it says : determine a table of values for the domain of integers within
-6< x< 6

then it says :5x+3y=26

and it has another problem

3x-3y=27
• Aug 28th 2009, 06:54 AM
artvandalay11
The area of a circle= $\pi r^2$ and the circumference= $2\pi r$ so set 64= $pi r^2$ solve for r anf plug into the circumference formula

I'm not sure why you're having a problem with the second one, draw a picture, but here's a hint
If the minute hand moves 30 minutes, it has moved 180 degrees, if it moves 15 minutes, then it moved 90 degrees

Area of triangle= $\frac{1}{2}$base*height
Area of rectangle= base*height

So $\frac{1}{2}(5)(5)=\frac{1}{3}5x$

The last problem is just asking for the y values of those equations when x=-5,-4,-3....,3,4,5
• Aug 28th 2009, 06:55 AM
stapel
Quote:

Originally Posted by student897
if the area of a circle is 64pi, then what is the circumfrence?

Look up (and re-memorize) the formulas for the area A and the circumference C of a circle with radius r. Plug the given value into the appropriate formula, and solve for the value of r. Then plug this into the other formula to find the required value.

Quote:

Originally Posted by student897
if the minute hand of a clock moves 45 degrees, how many minutes of time have passed?

Review the concept of "degrees" (in particular, how many degrees are in a circle), and then look at an analog (that is, non-digital) clock. Count the minutes.

Quote:

Originally Posted by student897
a triangle of height 5 and base 4 has an area exactly 1/3 that of a rectangle with height 5 . what is the width of the rectangle?

Look up (and re-memorize) the formulas for the areas A of a triangle with base b and height h and of a rectangle with length L and width w. Plug the given values into the appropriate formula.

Then note that, if the triangle is one-third of the rectangle, then the rectangle is three times of the triangle. Plug this, and the given value, into the other formula, and solve for the required value.

Quote:

Originally Posted by student897
it says : determine a table of values for the domain of integers within -6< x< 6 then it says :5x+3y=26

Look up what "integers" are. Then review how to evaluate expressions. In this case, you'll be evaluating "5x + 3y = 26" for given values of x, and then solving for the corresponding values of y. Then you'll make a table, or chart, listing these pairs of values.

Quote:

Originally Posted by student897
3x-3y=27

Lacking instructions for this exercise, I'm afraid I cannot advise. Sorry. (Wondering)
• Aug 28th 2009, 06:58 AM
Quote:

Originally Posted by student897
i dont understand these problemss.....please help me on them i got a summer packet and i dont understand almost none of the problemsss(Crying)anyway here are the problems

if the area of a circle is 64pi, then what is the circumfrence?

$\pi r^2=64\pi$ , calculate r , then put it into $S=2\pi r$

if the minute hand of a clock moves 45 degrees, how many minutes of time have passed?

45/360x60=...

a triangle of height 5 and base 4 has an area exactly 1/3 that of a rectangle with height 5 . what is the width of the rectangle?

1/2(5)(4)=1/3(5w) , calculate w where w is width .

here are some other problems i dont understand..

it says : determine a table of values for the domain of integers within
-6< x< 6

then it says :5x+3y=26

y=(26-5x) / 3 , so within the domain of -6<x<6 , what would the y's be?

Then you will need to substitute one by one , ie -6 , -5 , -4 , ... , 6

and it has another problem

3x-3y=27

Same method .

.
• Aug 28th 2009, 07:11 AM
student897
i understand now.. =]
• Aug 28th 2009, 09:41 AM
Wilmer
Why did you not understand BEFORE? Miss classes? Poor teacher?
• Aug 30th 2009, 09:18 AM
student897
Quote:

Originally Posted by Wilmer
Why did you not understand BEFORE? Miss classes? Poor teacher?