4F Finding unknown sides
USING TRIGONOMETRIC RATIOS
Use trigonometric ratios to calculate side lengths of right-angled triangles and to solve problems.
TASK 1
Measure and check
Check whether the tangent ratio actually works.
Measure the angle A to the nearest degree.
Measure side AC as accurately as possible.
Use the tangent ratio to calculate the length of BC.
Now measure BC to check that using trigonometry gave you
the correct length (within accuracy levels).
TASK 2
Calculate side lengths (tan)
Use the tangent ratio ratio to find the length of the side opposite the given angle, correct to 2 decimal
places where needed.
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Ch4 Right-angled triangles
4F Finding unknown sides
TASK 3
Calculate side lengths (sin and cos)
Use the sine or cosine ratio to find the value of each pronumeral in these right-angled triangles. Round
answers to 2 decimal place.
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TASK 4
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Solve problems
Choose an appropriate trigonometric ratio to solve these problems.
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Sam stood on the sideline of a football field,
20 m from the corner post. His line of sight to
the other corner post made an angle of 66° to
the sideline. Find the approximate width of the
field.
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Ch4 Right-angled triangles