Kristie bought 4 drinks for $1.99 each and 4 muffins for $1.20 each at the local café. She left a $2.30 tip for the server. How
2 answers:
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Answer:
see explanation
Step-by-step explanation:
Using sum to product identities
cos x - cos y = - 2sin( )sin(
) = 2sin(
)sin(
)
cos x + cos y = 2cos( )cos(
)
Note that
sin10° = sin(90 - 10)° = cos80°
Thus
← cancel 2 from numerator/ denominator
= ×
= tan45° × tan35° { tan45° = 1 ]
= 1 × tan35°
= tan35° ← as required