How do you express $cos( (15 pi)/ 8 ) * cos (( 2 pi) /3 )$ without using products of trigonometric functions?

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How do you express $cos( (15 pi)/ 8 ) * cos (( 2 pi) /3 )$ without using products of trigonometric functions?

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Answer 1 · 2016-05-14T05:14:30

$-(1/2)cos (pi/8)$

Explanation:

$P = cos ((15pi)/8)cos ((2pi)/3)$
trig table gives -->cos (2pi)/3 = - 1/2
$cos ((15pi)/8) = cos (-pi/8 + (16pi)/8) = cos (-pi/8 + 2pi) =$
$= cos (-pi/8) = cos (pi/8)$
Therefor, P can be expressed as:
$P = -(1/2)cos (pi/8)$

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How do you express $cos( (15 pi)/ 8 ) * cos (( 2 pi) /3 )$ without using products of trigonometric functions?

1 Answer

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Science

Math

Humanities

... and beyond

How do you express cos( (15 pi)/ 8 ) * cos (( 2 pi) /3 ) cos( (15 pi)/ 8 ) * cos (( 2 pi) /3 ) without using products of trigonometric functions?

1 Answer

Explanation:

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How do you express $cos( (15 pi)/ 8 ) * cos (( 2 pi) /3 )$ without using products of trigonometric functions?