# what is tangent cosine and sine?

#### fallinbehind

##### New member
I have no idea i missed a few days of math and don't know how to answer any of the questions. I' supposed to find the exat measure of the variables in the right triangles and all i know is one side length and one angle other than the 90 degree angle. Please help

G

#### Guest

##### Guest
if you give me the numbers i will give you the equation to figure it out

#### tkhunny

##### Moderator
Staff member
fallinbehind said:
I'm supposed to find the exat measure of the variables in the right triangles and all I know is one side length and one angle other than the 90 degree angle. Please help
You should have a small table of frequently used values. Find it in your book or ask your teacher where to find it. You should memorize it.

#### fallinbehind

##### New member
wel... it is a right triangle one of the side lengths is 8 and one of the angles is 45 degrees is that what you meant?? i'm kind of confused i missed four days of math

#### fallinbehind

##### New member
wait what is the table for???? i'm like four days and two sections behind i have no idea what tangent cosine sine is or what they are used for

#### tkhunny

##### Moderator
Staff member
You're in luck. 45º is one of the values that will be on the table of useful values.

sin(45º) = cos(45º) = $$\displaystyle \frac{1}{2}\sqrt{2}$$

#### fallinbehind

##### New member
but how do i use that equation what numbers do i plug in and what will it help me solve????

#### tkhunny

##### Moderator
Staff member
You need a book and a teacher. Do you have those? It's time to catch up.

G

#### Guest

##### Guest
to find the other angle do 180-90-45 and you will get the angle....
to find the sides do 8/cos45....then do that for the other side

#### fallinbehind

##### New member
yeah but i'm like one of 4 8th graders in a tenth grade math class so i wlak to the high school for math and then back to the middle school and i just don't know how i'm going to manage to get four days worth of extra help and i have a test on tuesday...

#### fallinbehind

##### New member
thanx for all the help

G

#### Guest

##### Guest
no problem...i know how getting stuck in math is...thats why im here too

#### Concorde

##### New member
It's very important you understand how the trig functions are defined, they will be very useful in your future math classes and science classes like physics.

First, note the trig. functions are for right triangles, if you have a triangle of another type you must either divide it in such a way so that it is a right triangle or you need to use the law of sines/law of cosines (which is something you will probably talk about fairly soon in your class).

A will stand for the angle in my examples below.

Sin A = length of side of triangle opposite the angle/ length of the hypotenuse

Cos A = length of side adjacent to angle/ length of the hypotenuse

Tan A = length of side opposite the angle/ length of side adjacent to the angle

These aren't all of the trig identies (There are 3 more, they are basicaly defined as 1/cos, etc so learning these is important!) but they are the basic ones.

You will certainly want to get help from your teacher/consult your math book to be sure you understand this and understand it well.