Posted by Andy on Wednesday, July 15, 2009 at 11:08pm.
A rectangle has area 6 cm (squared) and diagonal of length 2√5 cm. What is its perimeter?
thanks

math  Reiny, Thursday, July 16, 2009 at 8:49am
let the width be x and the length be y
we know xy = 6 and
x^2 + y^2 = (2√5)^2 = 20
Perimeter = 2(x+y)
from algebra we know
(x+y)^2 = x^ + 2xy + y^2
but we know the values on the right side,
so
(x+y)^2 = 20 + 6 = 26
then x+y = √26
and the perimeter is 2√26

math  David, Wednesday, July 29, 2009 at 8:33am
let the width be x and the length be y
we know xy = 6 and
x^2 + y^2 = (2ã5)^2 = 20
Perimeter = 2(x+y)
from algebra we know
(x+y)^2 = x^ + 2xy + y^2
but we know the values on the right side,
so
(x+y)^2 = 20 +12=32
then x+y = ã32
and the perimeter is 2ã32

math  David, Wednesday, July 29, 2009 at 8:38am
Why is math so hard?
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