Posted by Josh on Monday, February 23, 2009 at 6:58pm.
The area of a rectangle is 90m 2. The base is three less than three times the height. What is the perimeter?
- Math - Damon, Monday, February 23, 2009 at 7:38pm
b = 3 h -3
area = b h = (3 h - 3)h = 3 h^2 - 3 h = 90
3 h^2 - 3 h - 90 = 0
(h+5)(3h-18) = 0
h = 6 is positive real solution
b = 3*6 -3 = 15
then perimeter = 2 h + 2 b
- Math - Josh, Monday, February 23, 2009 at 7:54pm
dont get it
- Math - Josh, Monday, February 23, 2009 at 8:06pm
how did you get that. not rudely.
- Math - PsyDAG, Tuesday, February 24, 2009 at 10:36am
Let B = base and H = height
From the first sentence:
B * H = 90
From the second sentence:
B = 3H - 3
Substitute the value of B from the second equation into the first and solve for H. Put the value of H in the second equation to find B. Check by putting both values into the first equation.
As Damon says, "then perimeter = 2 h + 2 b".
I hope this helps. Thanks for asking.
Answer this Question
More Related Questions
- basic geometric - 10. a rectangle has width the same as a side of a square whose...
- geometry - the perimeter of a rectangle is 72. the base is 3 times the height ...
- algebra - The perimeter of a rectangle is 80x. The base is 7 times the height. ...
- math - The area of a rectangle is 77 yd2 , and the length of the rectangle is 10...
- Math - The area of a rectangle is 220 square centimeters. The height of the ...
- 9th grade polynomials - How do you write the expression for the area of the ...
- Algebra - The length of a rectangle is three times its width. If the area of the...
- Algebra - The length of a rectangle is 8 ft less than three times the width, and...
- maths - the length of a rectangle is 3 less than 5 times its width. Write a ...
- pre calc - The length of a rectangle is three times its width. If the area of ...