Transcript activity 2 - Yukon Education Grade 10 Mathematics

ACTIVITY 2 - HOW TALL IS… ?
Tuesday November 30th, 2010
Rollie Comeau
Watson Lake Secondary School
ACTIVITY 2
How tall is …?
Specific Outcomes
A.3 - 3.1 and 3.2
B.2 - 2.3 and 2.7
B.3 - 3.5, 3.6 and 3.7
B.4 - 4.1 and 4.2
B.5 - 5.1, 5.4, 5.7, and 5.8
ACTIVITY 2
How tall is …?
Material needed:
Protractor
Tape
Weight
Paper
Warm Clothing
Tube (one foot long)
String
Pencil
Calculator
ACTIVITY 2
How tall is …?
Problem
You need to cross a particularly swift
creek. It is too wide to jump. A tree
stands close to the edge of the creek.
How can you determine if the tree is
long enough to safely span the creek?
ACTIVITY 2
How tall is …?
Tree
Ground Distance
ACTIVITY 2
How tall is …?
To solve this problem, the concepts of
similar triangles, right-triangles,
trigonometry, parallel lines and
transversal lines, and/or referents can
be introduced in your lesson.
ACTIVITY 2
How tall is …?
Let’s use trigonometry to solve this
problem.
The three basic trigonometric ratios
involve two sides of a right-triangle
and one of the two acute angles.
ACTIVITY 2
How tall is …?
In our case, we are looking for the height
of the tree - this is the unknown value
we are seeking.
ACTIVITY 2
How tall is …?
The distance from the tree can be
assessed with the help of a long
measuring tape.
This is one of our known values.
We are missing an acute angle…
ACTIVITY 2
How tall is …?
From the ground, looking up at the top
of the tree, we could possibly
determine the angle of elevation. For
this, you will need to consult a
surveyor who can measure it for you or,
construct a simple device that can do
it for you!
ACTIVITY 2
How tall is …?
A simple clinometer comes to mind…
let’s construct one!
ACTIVITY 2
How tall is …?
Before going outdoors, you will need to
determine the height of your eyesight.
For convenience, a measuring tape has
been placed on the wall to assist you.
Record this value on the Activity 2 data
sheet provided.
ACTIVITY 2
How tall is …?
As a group, select a set distance from
the object to be measured. Record this
value as “Ground Distance”.
ACTIVITY 2
How tall is …?
Each member of the team should:
a) Use the clinometer (viewing through
the tube at the top of the tree)
b) Take the reading off the clinometer
(angle in degrees)
c) Record the measurement read by b)
ACTIVITY 2
How tall is …?
Upon return,
a) Draw a diagram representing the
problem we are attempting to solve
b) Place all measurements in the
diagram
c) Use trigonometry to solve the
problem
ACTIVITY 2
How tall is …?
Share your answer with your group.
1. Discuss why your answer may vary
compared to others.
2. Discuss factors that may influence
your answers.