Introducing the Topic
Chapter 7 considered techniques of finding the solution to problems involving
right triangles. This chapter explores using the calculator with the Law of Sines
and Law of Cosines. These two laws relate the angles and lengths of the sides
of any triangle and have been used for many centuries in solving practical
problems such as those that occur in map making, navigation, and surveying.
Calculator Operations
Before using the calculator to solve problems in this chapter, set the calculator
to operate in degrees by pressing 2ndF SET UP , touching
B DRG
, and double
touching
1 Deg
. Press 2ndF QUIT to exit the set up screen.
The Law of Sines states that the ratio of the lengths of the sides of a triangle to
each other is the same as the ratio of the sines of the angles opposite the sides.
That is, if A, B, and C are the measures of the three angles of a triangle and X, Y,
and Z are respectively the lengths of the three sides opposite those angles, then:
= =
34
Law of Sines and Law of Cosines/TRIGONOMETRY USING THE SHARP EL-9600
LAW OF SINES AND
LAW OF COSINES
Chapter eight
sin A
X
sin B
Y
sin C
Z
(
(
(
A
B
C
Y
X
Z