Transcript What Else Can We Do With Trigonometry?

What Else Can We Do
With Trigonometry?
Accelerated Math II
October 24, 2008
One Minute Question
In the triangle below, write the
value of cos A in simplest form.
A
26
C
24
B
One Minute Question
In the triangle below, find
cos A.
adj 10 5
cosA 


A
hyp 26 13
10
26
C
24
B
Homework Questions?
Quilt Design Task
• The Friendship Quilt Block is the first one
from your task. If the segments shown are
the length of the straw, cut segments to
complete the diagonals of the quilt square.
The Empire State Building
From a point 100’ from
the base of the Empire
State Building, the
angle of elevation to
the top is 86º. Based
on this information,
how tall is the Empire
State Building?
The Empire State Building
From a point 100’ from the base of the
Empire State Building, the angle of
elevation to the top is 86º. Based on
this information, how tall is the
Empire State Building?
h
tan 86 
100
100  tan 86  h
h  1430'
h
100’
Angles…
• As you know, the calculator
knows the sine, (cosine and
tangent) of every acute angle.
So, if we know what the sine of
an angle is, can we find the
angle???
Angles…
Try this…
You know that the sin 30º = .5,
So if we type in .5, can we get
the calculator to give us 30??
Angles…
So check by finding the smallest
angle in a 3-4-5 right triangle.
5
3
θ
4
Since sin θ = 3/5, the
angle can be found
by…
And it is 36.87º
Angles…
So, if we know an angle measures
50º, we can find the sine of that
angle by
Typing 
But if we know that the sine of an
angle is .46, we can find the angle
By typing 
Finding sides and angles…
Solve this triangle.
A
14
B
9
C
Solve this triangle.
A
a2 + b2 = c2,
14
a2 + 92 = 142
a2 + 81 = 196
a2 = 115, so
BC = 115 = 10.72
B
9
C
9
1 9
cosA 
, so A  cos
14
14
So, type  to get
m A = 49.99 º. And, mB = 90º – 49.99º
= 40.01º
Homework
Pg. 168: 1-7, 16-19
Pg. 174: 1-24 odd, 25-27
Quiz Monday on Special Right Triangles and
basic trig definitions – so review special
right triangles and trig definitions…