Happy Tuesday
• Sit in the general location of where youy
previously sat, but do not get too comfy. Some
of you will be moving!
Tonight’s HW:
• p 555 # 1-12
8.5: Law of Sines
Learning Objective:
• SWBAT use Law of Sines to solve triangles.
So far, we have only use trig functions to
calculate missing sides of right triangles.
But what if we have an obtuse or an acute
triangle?
Today is your LUCKY day! We are going to use
Law of Sines to calculate measures of other
triangles.
You can use the altitude of a triangle to find a
relationship between the triangle’s side lengths.
In ∆ABC, let h represent the length of the
altitude from C to AB.
You can use the Law of Sines to solve a triangle if you are
given
• two angle measures and any side length
• two side lengths and a non-included angle measure
EX1: Practice with a Calculator
A. tan 103°
B. cos 165°
C. sin 93°
It is okay if you get a negative number!
Example 2: Using Law of Sines
Find the measure. Round lengths to the nearest
tenth and angle measures to the nearest degree.
a) FG
b) FH
Example 3
Find the measure. Round lengths to the nearest
tenth and angle measures to the nearest degree.
mL
Whiteboard
Find the measure. Round lengths to the nearest
tenth and angle measures to the nearest degree.
MX
Whiteboard
Find the measure. Round lengths to the nearest
tenth and angle measures to the nearest degree.
NP
Whiteboard
Find the measure. Round lengths to the nearest
tenth and angle measures to the nearest degree.
AC
Whiteboards
Leaning Tower of Pisa!
The Leaning Tower of Pisa is 56 m tall. In 1999, the tower made a
100° angle with the ground. To stabilize the tower, an
engineer considered attaching a cable that is 74.3m from the
top of the tower to a point that is 40 m from the base. What
angle does the cable make with the ground? Round to the
nearest degree.