Download TRIG – THE EASY WAY

TRIG – THE EASY
WAY
Trig functions
To remember the trigonometry functions, use the memory aid:
Soh
Cah
Toa
The first letter of each aid represents the function. The last two letters indicates the
ratio of sides needed to calculate the function.
Soh --> Sine = opposite/hypotenuse
Cah --> Cosine = adjacent/hypotenuse
Toa --> Tangent = opposite/adjacent
We can use trigonometry functions to determine:
•
one acute angle if you know two sides
•
one of the sides if you know an acute angle and one side
HYPOTENUSE, OPP. LEG,
& ADJ. LEG
HYPOTENUSE
OPP. LEG
ADJ. LEG
TO FIND A MISSING SIDE
21
?
42°



Determine what trig
function to use
Set up the equation
that solves the
situation
Solve the equation
and round answer
appropriately
21
?
42°
DETERMINING THE FUNCTION
hypotenuse
21
42°
Opposite / hypotenuse >>>>>>>>>
SINE
?
Opp
solution





Sin 42° = x / 21
.6691 = x / 21
X = (.6691) (21)
X= 14.0511
X= 14.1
TO FIND A MISSING ANGLE
8
?
15
DETERMINE THE FUNCTION.
OPPOSITE
8
?
15
ADJACENT
OPPOSITE / ADJACENT >>>>>>>>> TANGENT
PROCESS AND SOLUTION

Determine the function ----> Tangent

Write the equation ----------> Tan

D = 8 / 15
Solve the equation ---------> Tan D = .5333
Note : you must use the inverse of tangent to find the angle:
-1
tan or arctan on your calculator.
‹D = tan-1(0.5333)
‹D = 28.072487
‹D = 28º