HELP!!! -how do you work out one length (side) of a triangle when you know the other two lengths??

Question

if one length is 8 cm and the other is 11cm how do you work out the other side????

PLEASE HELP!!

Answer 1

If it is a right triangle; A squared = B squared + C squared

Answer 2

What do you know about the face of a clock? There are twelve segments (the hours) and four is one-third of the way around the face. Since a full circle is 360 degrees, then the four must be 120 degrees around the centre, right? So you now know the angle between the two hands (two sides of the triangle) as well as the length of the two sides. I'm sure you can calulate the length of third side now...

Answer 3

use Pythagoras theorem: (a)^2 + (b)^2=(c)^2

c is the hypotenuse(opposite the right angle)

a and be are the adjacent and opposite (two lines which make up the right angle)

when squaring the numbers make sure it is in brackets, not so crucial with whole numbers or decimals but with fractions it will matter as without the brackets it will only square the denominator giving you an incorrect answer

here is an example when you don't know C

(a)^2 +  (b)^2 =(c)^2

(8)^2 + (11)^2=(c)^2

64+ 121=(c)^2

185=(c)^2

c=square root of 185 =13.6cm (1d.p)

so on this triangle C will be 13.6

example 2 when we don't know a or b (doesn't matter which one you choose and c is always the longer side)

(a)^2 +  (b)^2 =(c)^2

(a)^2 + (8)^2 = (11)^2

(a)^2 + 64 = 121

(a)^2=121 - 64

(a)^2=57

a=square root of 57 = 7.54cm (1d.p)

Answer 4

The third side could be almost any length unless you are given some constraints.

For example, is it a right triangle, are you give the measure of any of the angles,...? What other information do you have about this triangle?

Answer 5

If you are really bad on math and good on drawing, do it on  cross hatch paper, it works.

Answer 6

you need the angle opposite the side you want to find.

the side you want to find is c

the angle opposite it is C

the other two sides are a and b

so

c^2=(a^2)+(b^2)-(2abcosC)

if the angle C is 90 then cos 90 is 0 so 2abcos Cis 0 therefore c^2=(a^2)+(b^2)

Answer 7

you are given an angle. At four o'clock the hour hand has traversed one third of the way about the face. The angle is, therefore, 120. You can use cosine law given above.

Answer 8

do you know an angle?i don't think there is a way to find the third length otherwise..