Question
1)
Use an Addition or Subtraction Formula to write the expression as a trigonometric function of one number.
cos 12° cos 18° − sin 12° sin 18°
And Find its exact value.
2)
Use an Addition or Subtraction Formula to write the expression as a trigonometric function of one number.
sin 4pi/5 cos 7pi/15 - cos 4pi/5 sin 7pi/15
And find its exact value.
3)
Write the trigonometric expression in terms of sine and cosine, and then simplify.
tan θ / cos θ − sec θ
Use an Addition or Subtraction Formula to write the expression as a trigonometric function of one number.
cos 12° cos 18° − sin 12° sin 18°
And Find its exact value.
2)
Use an Addition or Subtraction Formula to write the expression as a trigonometric function of one number.
sin 4pi/5 cos 7pi/15 - cos 4pi/5 sin 7pi/15
And find its exact value.
3)
Write the trigonometric expression in terms of sine and cosine, and then simplify.
tan θ / cos θ − sec θ
Answers
1) that would be cos(12°+18°) which I'm sure you know
2) sin(4π/5-7π/5)
3)
well,
tan/cos = sin/cos^2 and sec = 1/cos
2) sin(4π/5-7π/5)
3)
well,
tan/cos = sin/cos^2 and sec = 1/cos
Thank you so much but are those the expressions or exact answers for the first two problems?
they are expressions. You surely know the exact value of cos(30°)
as for sin(-3π/5) you would have to construct a pentagon and figure out some side lengths. figure out sin 36° and then sin 72° and then the sine of 108°.
as for sin(-3π/5) you would have to construct a pentagon and figure out some side lengths. figure out sin 36° and then sin 72° and then the sine of 108°.
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