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# The hypotenuse of a right triangle is 15 centimeters long. one leg is 9 cm long. How long is the other leg? ?

please help? im so confused.

### 14 Answers

- 1 decade agoFavorite Answer
use the pythagoreon thyrom

a^2 + b^2 = c^2

9^2 + x^2 = 15^2

81 + x^2 = 225

x^2 = 144

x = 12 cm

- Anonymous1 decade ago
The Pythagorean theorem says that the sum of the squares of the legs of a right triangle equals the square of the hypotenuse.

You have all the elements to apply Pythagorean theorem.

x^2 + 9^2 = 15^2

x^2 + 81 = 225

x^2 = 144

x = 12 cm

- Anonymous1 decade ago
Pythagorean Theorem: side^2 + side ^2 = hypotenuse^2

a^2 + b^2 = c^2;

a^2 + 9^2 = 15^2

subtract 9^2 from both sides to find a^2

a^2 = 15^2 - 9^2

a^2 = 225 - 81

a^2 = 144

take the square root of both sides

a = √144

a = 12

- Weird-OLv 51 decade ago
well a squared plus b squared equals c squared. ( a and b being the legs and c being hypotenuse. ) Square the first leg (81) and the hypotenuse (225) now subtract 81 from 225 to get b by itself in the equation 81 + b =225

225-81=144

now b squared = 144

take square root of 144

you get 12

the other leg is 12

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- а●м℅²°¹²Lv 41 decade ago
12

if you think about it, i'm sure you know that 3,4, & 5 and 5, 12, & 13 are the basic right triangle lengths.

so 15 and 9 are the 3, 4, 5 sequence just times 3.

5 x 3 = 15

3 x 3 = 9

so the other side has to be

4 x 3 = 12 !!!

- 1 decade ago
a^2+b^2=c^2 where a and b are legs and c is hypotenuse. Plug the information in, and you get 12.

- 1 decade ago
a^2 + b^2 = c^2 where a and b are the two legs of a right triangle and c is the hypotenuse. So,

a^2 + (9cm)^2 = (15cm)^2

a^2 + 81cm^2 = 225cm^2

a^2 = 144cm^2

a = 12cm

- Anonymous1 decade ago
a squared + b squared = c squared.

the hypotenuse is always c.

so 15 x 15 = 225

minus b squared which is 9 x 9 = 81

so 225 - 81 is equal to a.

get it?

- Anonymous1 decade ago
a squared + b squared = c squared

c always being the hypotenuse

so 15 squared is 225 while 9 squared is 81

plug it in

81 + bsquared = 225

subract 81

bsquared = 144

Find the square root of 144

Which is 12.

- 1 decade ago
use the formula:

a^2+b^2=c^2

then plug ur numbers in:

9^2+b^2=15^2

then square the known numbers

you get:

81+b^2=225

then subtract 81 from each side to get b^2 by itself

you get:

b^2=144

then take the square root of each side to get b by itself

you get:

b=12

and that's your final answer

Source(s): my brain