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Right Triangles
This is a right triangles.
In a right triangle we call the longest side (the one that is opposite the right angle) the hypotenuse.
The other sides are called legs. Below is a picture of a right triangle. The vertices are labeled with capital letters A,
B, and C. The lower case letters represent the lengths of the sides. Notice that the side a is opposite angle A and so on.
The side AB is the hypotenuse.
PYTHAGOREAN THEOREM
Rule relating the lengths of the sides of a right triangle. It says that the sum of the squares Rule relating the lengths
of the sides of a right triangle. It says that the sum of the quares of the lengths of the legs is equal to the square of
the length of the hypotenuse (the side opposite the right angle). That is, a2 + b2 = c2,
where c is the length of the hypotenuse. of the lengths of the legs is equal to the square of the length of the hypotenuse
(the side opposite the right angle). That is, a2 + b2 = c2, where c
is the length of the hypotenuse.
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S O H C A H T O A
i p y
o d y a
p d
n p p s j p n p j
o o i a o g
o a
s t n c t e s c
i e e e e n
i e
t n
n n t t n
e u
t u e t
s s
e
e
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TRIGONOMETRIC RATIOS
The relationships between the angles and the sides of a right triangle are expressed in terms
of TRIGONOMETRIC RATIOS. For example, in figure 19-7, the sides of
the triangle are named in accordance with their relationship to angle q.
In trigonometry, angles are usually named by means of Greek letters.
The Greek name of the symbol q is theta.
The six trigonometric ratios for the angle q are listed in table 19-1.
The-ratios are defined as follows:
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, 
, and 
.