Trigonometry

1. File
MC MATH 3 TRIGONOMETRY
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B I U
ANGLE
MEASUREMENT
REPORT OF EVANGELISTA AND VILLAMER

2. Objectives:
understand the radian measure
learn the method for converting degree to
radians and vice-versa
convert between degree and radian
measurements
At the end of the lesson, the learners are
expected to:

3. RADIAN
Page 3
is the measure of an
angle θ that, when
drawn as a central
angle, subtends an arc
whose length equals the
length of the radius of
the circle.

4. ARC LENGTH
is the distance
between two points
along a section of
a curve.
The formula for getting
the arc length:
s=rθ
where s= arc length,
r=radius, and θ= radian
measure
Page 4

5. RADIUS
defined as a line
segment joining the
center of the circle
or a sphere to its
circumference or
boundary
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The formula for getting
the radius:
r=s/θ
where s= arc length,
r=radius, and θ= radian
measure

6. WHAT IS THE RADIAN
MEASURE OF CENTRAL
ANGLE AOB?
You want the arc length and the
radius to have the same units, but
they are given to you in inches
and feet. You could convert either
one. The arc determined by ∠AOB
has length s= 48 inches.
In this circle, r= 2 feet.
Substitute this and the value
above for into the formula.
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7. THE CENTRAL ANGLE
SHOWN HAS A MEASURE OF
1/2 RADIAN. WHAT IS
THE LENGTH OF ARC CD?
In this circle, r= 4
inches. You know that
θ= 1/2 . Substitute
these numbers into the
arc length formula.
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8. IF THE LENGTH OF ARC
EF IS 42 MM AND THE
MEASURE OF ∠EOF IS 3
RAD, WHAT IS THE
LENGTH OF THE RADIUS?
You are given that s=42 mm,
and θ= 3. Substitute these
values into the arc length
formula.
Solve the equation for r.
Rewrite as a mixed number.
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9. CONVERTING
FROM DEGREES
TO RADIANS AND
VICE-VERSA
Page 9

10. DEGREES TO
RADIANS
To convert degrees to
radians, multiply the
given number of degrees by
π/180°.
Example:
50°-> 50 ° ⋅ π/180°= 5π/18
radians
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11. To convert radians to
degrees, multiply the given
number of radians by 180°/
π.
Example:
5π/6 rad -> 5π/6 ⋅ 180°/π =
150°
Page 11
RADIANS TO
DEGREES

12. File
Thank You
For Listening
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Do you have any questions?

13. QUIZ

14. QUIZ