Question

If the length of a rectangle is increased by a factor of 5/2 and the width is decreased by a factor of 1/2, by what factor does the area change?
A. look at the picture
B. 2
C. 3
D. 10

Answer 1

please help, ill give medals

Answer 2

multiply the fractions because
A=LW
where A is area
L is length
W is width

if you have a 2x3 rectangle
area is 2x3=6

if you change the length by a factor of 1/2
and the width by a factor of 5/2
you get
\[A=\frac{ 5 }{2? } \frac{ 1 }{ 2 } LW\]

Answer 3

so just multiply your fractions to get the factor that the area changes

Answer 4

tysm, can you help me with one more please?

Answer 5

i can try

Answer 6

Triangle ABC is similar to triangle DEF If the area of Triangle DEF is 567cm^2, what ratio would you multiply 567 by to find the area of Triangle ABC

Answer 7

do you have a picture?

Answer 8

you know the hypotenuse on the first triangle is 100
the second triangle the hypotenuse is 75
75/100 is 3/4

so your factor that the triangle has changed by is 3/4

work out the sides of the second triangle by doing 60x3/4
and 80x3/4

then use the formula to work out the area of a triangle
A=0.5(bxh)

to get
0.5(45x60)

divide this by the area of the first triangle

and you will get a ratio which is 9/16

so the factor which changed the size of the triangle is 3/4
our answer is 9/16

therefore to figure out the factor the area changes is the size factor squared

so 9/16 is your answer

Answer 9

9/16 isn't an answer choice

Answer 10

a.4/9
b.8/9
c.16/9
d.48/9

Answer 11

@amorfide

Answer 12

then i dont know because I worked it out to be 9/16

Answer 13

ok thanks