4.2 Proving and Applying SIne and Cosine Laws for Obtu.notebook
January 09, 2017
4.2 Proving and Applying the Sine
and Cosine Laws for Obtuse Angles
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4.2 Proving and Applying SIne and Cosine Laws for Obtu.notebook
January 09, 2017
An isosceles triangle has one angle that measures 1200 and
one side length that is 5 cm. What could the other side
lengths be? Draw a picture!
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4.2 Proving and Applying SIne and Cosine Laws for Obtu.notebook
January 09, 2017
Does the sine law work for obtuse triangles?
3
4.2 Proving and Applying SIne and Cosine Laws for Obtu.notebook
January 09, 2017
Does the sine law work for obtuse triangles?
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4.2 Proving and Applying SIne and Cosine Laws for Obtu.notebook
January 09, 2017
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4.2 Proving and Applying SIne and Cosine Laws for Obtu.notebook
January 09, 2017
Example 1: In an obtuse triangle, angle B =230 and its
opposite side,b, has a length of 40 cm. Side a is the
longest side of the triangle, with a length of 65 cm.
Determine the measure of angle A to the nearest degree.
What is the length of side c?
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4.2 Proving and Applying SIne and Cosine Laws for Obtu.notebook
January 09, 2017
Cathy & Mike observed a tethered balloon advertising the opening of a
new fitness center. They were 250 m apart, joined by a line that passed
directly below the balloon, and were on the same side of the balloon.
Mike observed the balloon at an angle of elevation of 70 while Cathy
observed the balloon at an angle of elevation of 820 Determine the
height of the balloon to the nearest meter.
How far is Mike from the balloon?
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4.2 Proving and Applying SIne and Cosine Laws for Obtu.notebook
January 09, 2017
The roof of a house consists of two slanted sections, as
shown. A roofing cap is being made to fit the crown of
the roof, where the two slanted sections meet.
Determine the measure of the angle needed for the
roofing cap, to the nearest tenth of a degree.
Find the angle of elevation for each roof section , to the nearest tenth
of a degree.
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4.2 Proving and Applying SIne and Cosine Laws for Obtu.notebook
January 09, 2017
Keep in Mind ...
Caution!
When using sine, you need to decide which angle to
use - acute or obtuse
When using cosine, the measures are always correct as
the angle and its supplement are opposites, not equal
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4.2 Proving and Applying SIne and Cosine Laws for Obtu.notebook
January 09, 2017
Assignment:
p 170 1-5, 6ab, 7
choose 3 from 9-12
choose either 13 or 14
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