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3 years ago

Show cos 20 * cos 40 * cos 80 =1/8

1 answer:

8 0

cos 20 cos 40 cos 80 =
= ( 2 sin 20 cos 20 cos 40 cos 80 ) / 2 sin 20 =
( multiple and divide by 2 sin 20 )
= ( sin 40 cos 40 cos 80 ) / 2 sin 20 =
= ( 1/2 sin 80 cos 80 ) / 2 sin 20 =
= ( sin 80 cos 80 ) / 4 sin 20 =
= 1/2 sin 160 / 4 sin 20 =
= sin 160 / 8 sin 20 = ( and since: sin 160 = sin 20 )
= 1 / 8

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Step-by-step explanation:

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3 years ago

If EF = 2x+13, FG = 20, and EG = 71 what's the value of x

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Answer:

Step-by-step explanation:

|<----------------- 71 ----------------------->|

E-----------------------F---------------------G

2x + 13 20

find: x

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3 years ago

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Answer:

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Step-by-step explanation:

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Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$