I NEED HELP.... ABOUT HOW TO ENLARGE a PICTURE?

Question

a picture that is 18cm by 24cm ,how do you enlarge it by 30%. i have problems with all the picture problems like this. please tell me how you the enlarge and reducing a picture by a percent

Answer 1

Enlarging a picture (or rectangle) by 30% means to enlarge its area by 30%. The area of the pic is 18cm X 24cm = 432cm^2 or centimeters squared or square centimeters.
The new area needs to be 130% of the old area or 1.3 times the old area.

(old area)(1.3) = new area
(432cm^2)(1.3) = 561.6cm^2

When a pic is enlarged or shrunk the length and width of the new pic needs to be in the same ratio as the old pic or the new pic will be distorted.

Ratio of length to width of old pic = ratio of length to width of new pic

18/24 = (18x)/(24y)
The only way this is true is if ‘x’ = ‘y’ so:
Substituting ‘x’ for ‘y’ one gets:
18/24 = (18x)/(24x)
The ‘x’s cancel since x/x = 1 and the two ratios are equal.

The area of the new pic is:
(18x)(24x) = 432(1.3)
18*24*x*x = 432(1.3)
432 x^2 = 432(1.3)
x^2 = 1.3
x = ± √1.3
x = ± 1.14017
Our answer is the positive root, since the negative root will yield a negative new length or new width when multiplied by the original length or width.
x = 1.14017
This is the multiplier for the old length and width.

(new length)(new width) = (new area)
(18 * 1.14017)(24*1.14017) = 561.6
20.52306 * 27.36408 = 561.59 = 561.6
New length = 20.52306cm
New width = 27.36408cm

NOTE:
This same principle applies to reduction of a pic.
Reduce by 25% then the new area would be 100% - 25% = 75% or 0.75 of original.
x^2 = 0.75
x = ±√0.75
Again our multiple is the positive root.
x= 0.866

(new length)(new width) = (new area)
(0.866*L)(0.866*W) = new area
(0.866)(0.866)L*W =new area
0.75*L*W = new area
Since L*W = old area
0.75*(old area) = new area

Answer 2

18 X 24 = 432 and the enlarged picture is 30% more in area, i.e 432 X 1.3 = 561.6 = 562 sq. cms approx. To get the individual dimensions, let us multiply 18 and 24 by the square root of 1.3, i.e. by 1.14 and we get 18 X 1.14 = 20.5 and 24 X 1.14 = 27.4

We confirm this: 20.5 X 27.4 = 561.7 = 562 sq. cms approx.

So, we need to make our original 18 X 24 to 20.5 X 27.4 cms

Answer 3

I'd count 18 * 1.30
and then 24 *1.30
Reducing 1 percent would be 0.99 times whatever needs reducing.

Answer 4

just multiply each measure (18x24 cm) by 1.3, that means "the original" (1 = 100%) plus the enlarging percentage (0.3 = 30%).

18 x 1.3 = 23.4
24 x 1.3 = 31.2

So, your bigger picture is 23.4 x 31.2 cm

Answer 5

find 30% of the area

Answer 6

(18 x 24).3 +(18 x 24) = 23.4 cm x 31.2 cm