Which expression is equivalent to 20c-8d
2 answers:
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Answer:
The correct prove will be:
Step-by-step explanation:
Multiply and Divide by
=
⇒ Let = Ф and 7Ф =
= sin2Ф sin3Ф sin5Ф ÷ 2cosФ
= 1/2(2sin2Фsin5Ф)sin3Ф ÷ 2cosФ
= (cos3Ф - cos7Ф) sin3Ф ÷ 4cosФ
= 1/2(2cos3Ф sin3Ф) ÷ 4cosФ ∵cos7Ф = 0
= sin6Ф ÷ 8cosФ
= sin(7Ф - Ф) ÷ 8cosФ
= (sin7ФcosФ - cos7ФsinФ) ÷ 8cosФ ∵sin7Ф = 1
= cosФ ÷ 8cosФ
= 1/8
Hence, The correct prove will be:
Keywords: prove, sinФ, cosФ
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