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prisoha [69]
3 years ago
5

3 Prove thatcos130°+cos 110+ cos10=0​

Mathematics
1 answer:
Evgesh-ka [11]3 years ago
5 0

We know, cos A + cos B = 2cos(C+D)/2 × cos(C - D)/2

So,

cos 130 + cos 110 + cos 10

cos 130 + 2cos (110+10)/2 × cos( 110-10)/2

cos 130 + 2cos 60 × cos 50

cos ( 180 - 50 ) + 2cos60 cos 50

We know, cos ( 180 - A ) = -cos A

2cos 60 cos 50 - cos 50

Also, cos 60 = 0.5

2×0.5 cos 50 - cos50

cos 50 - cos 50

0  = RHS.

Hence proved

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5 0
3 years ago
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3 years ago
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6 0
3 years ago
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3 years ago
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Answer:

The correct answer is A, 73

Step-by-step explanation:

First we have to arrange the whole numbers in ascending order. i-e from smallest to largest. Showing it as follows:

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Now we would find the median by taking the middle number. But this series consists of even numbers. There are 20 numbers. So we will take the middle two numbers and find their average like follows:

71 + 75 = 146/2  = 73

The answer is 73

8 0
3 years ago
Read 2 more answers
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