Download Lesson 2 intro to trig lesson

Basic Trig
New Words
Trigonometry:
the study of the properties
of triangles.
Trigonometric ratio:
ratio of the measures of 2 sides of a triangle.
New Words
Sine: written sin, read [sahyn]
Cosine: written cos, read [koh-sahyn]
Tangent: written tan, read [tan- juhnt)
New sayings
Some old horse, caught another horse, taking oats away.
Signs of happiness come after having tankards of ale.
Some of her children are having trouble over algebra.
Some out houses can actually have totally odorless
aromas.
SOH CAH TOA (read soh-kuh-toh-uh)
Has 3 sides:
Hypotenuse
Adjacent
Opposite
Right Triangle
The Hypotenuse is always across from the
right angle. It is the longest.
The other two will depend on what angle we
are dealing with
Right Triangle
The opposite side is across the triangle from
the angle.
The adjacent side is next to the angle. It is one
of the sides of the angle.
Right Triangle
Hypotenuse
Adjacent
Opposite
If we are talking about this angle then...
Right Triangle
Hypotenuse
Adjacent
Opposite
If we are talking about this angle then...
Sine
Sine is the ratio of the opposite side divided by the
hypotenuse.
C
opp
sin B =
hyp
5
3
opp
sin
C
=
B
hyp
4
3
5
4
5
Cosine
Cosine is the ratio of the adjacent side divided by the
hypotenuse.
C
adj
cos B =
hyp
5
3
adj
cos
C
=
B
hyp
4
4
5
3
5
Tangent
tangent is the ratio of the opposite side divided by the adjacent.
C
5
B
4
3
opp 3
tan B =
adj 4
opp 4
tan C =
adj 3
What’s up with the sayings
Some old horse, caught another horse, taking oats away.
opp
sin =
hyp
adj
cos =
hyp
opp
tan =
adj
Which ever one you like...
Some old horse, caught another horse, taking oats away.
Signs of happiness come after having tankards of ale.
Some of her children are having trouble over algebra.
Some out houses can actually have totally odorless
aromas.
SOH CAH TOA (read soh-kuh-toh-uh)
soak-a-toe-a
Find tan j
l
3
k
6
j
45
opp 3
tan J =
adj 6
Find cos j
l
3
k
6
j
45
adj 6
cos J =
hyp 45
now simplify
Find tan k
l
5
k
12
13
j
opp 12
tan K =
adj
5
Find sin k
l
5
k
12
13
j
opp 12
sin K =
hyp 13
Find cos k
l
5
k
12
13
j
adj 5
cos K =
hyp 13