Pls help me expand this expression
1 answer:
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Answer:
see explanation
Step-by-step explanation:
The formula for the Sine rule is
=
=
Where a, b and c are the sides of a triangle and A, B , C are the angles opposite the corresponding sides, that is
A is opposite side a, B is opposite side b, C is opposite side c
The sine rule is usually applied using a pair of the ratios, where
2 sides and an angle are known to find an unknown angle.
1 side and 2 angles are known to find an unknown side.
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2
There are 2 forms of the Cosine rule
(a) a² = b² + c² - (2bc cosA ) ← to calculate an unknown side
(b) cosA = ← to calculate an unknown angle
(a) is used given 2 sides of a triangle b and c are known with A being the included angle ( the angle between the 2 sides )
(b) is used when the 3 sides a, b and c are known
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3
If the angle A = 90° then cos90° = 0 and formula (a) becomes
a² = b² + c² ← that is Pythagoras' identity