Use an appropriate identity to find the exact value of the expression.

1 answer:

Montano1993 [528]3 years ago

7 0

We know that cos(a+b) = coa.cob-sia.sinb

cos(310+50) = coas(310).cos(50) -sin(310).sin(50)

1st) cos(310+50) cos(360) = 1

2nd) cos (310) = cos(50) and sin(310) = -sin(50)

3rd) 1= cos²(50) - [-sin²(50)]

1= cos²(50) + sin²(50)
, which is 1

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How many terms are there in a geometric series if the first term is 4, the common ration is 3 and the sum of the series is 160

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