cosine of 3 times pi over 10
sine of 7 times pi over 10
sine of 3 times pi over 10
(The clear version of the question is in the picture below)
Answer:
(b) cos(3π/10)
Step-by-step explanation:
The given expression matches the trig identity form for the cosine of the difference of two angles:
cos(α-β) = cos(α)cos(β) +sin(α)sin(β)
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To match the given expression exactly, we can choose ...
α = π/2
β = π/5
Then the difference is ...
α -β = π/2 -π/5 = (5/10)π -(2/10)π = 3π/10
The given expression can be shortened to ...
cos(3π/10)
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Additional comment
Sometimes it can be difficult to remember when the signs in trig identities match, and when they differ. The fact that cosines of smaller angles have larger values can be a peg on which to hang that hat.
The expression 'cosine of pi over 2 times cosine of pi over 5 plus sine of pi over 2 times sine of pi over 5'' can be rewritten as 'cosine of 3 times pi over 10' by using the cosine addition formula.
The question is related to the usage of trigonometric identities and laws, specifically the cosine addition formula. This formula is defined as: cos(a + b) = cos a cos b - sin a sin b. Looking at your original expression, we can identify a and b based on this definition, to make it align with the cosine addition formula structure. Let's pick a = pi/2 and b = pi/5.
Therefore, your original equation can be transformed as follows:
cos(pi/2)cos(pi/5) + sin(pi/2)sin(pi/5) = cos((pi/2) - (pi/5)) = cos(3pi/10).
So, the expression 'cosine of pi over 2 times cosine of pi over 5 plus sine of pi over 2 times sine of pi over 5' can be rewritten as 'cosine of 3 times pi over 10.' We have used the cosine addition formula to simplify the original expression.
#SPJ3
Answer:
4
Step-by-step explanation:
f(-3) = 2 * (-3) + 10
If arc ADB is that portion of the circle that is not arc AB, then its measure is ...
... 360° -49° = 311°
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The sum of the measures of the arcs of a circle is 360°.
HELP Please
Answer:
it is 10 because 5x2= 10and20-10=10