Question

The question is : If A+B+C = 270 degrees then what is the value of: cos2A + cos2B + cos2C + 4sinA X sinB X sinC. I'll mark as Brainliest. 50 points.

Answer 1

Hey mate!

Here's your answer!!

Kindly refer to the given attachment .

And 270° = 3π/2 only.

Hope it helps you!

Answer 2

HEY MATE HERE IS YOUR ANSWER

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Let's solve in different points by considering smaller units

Cos2a + Cos2b = 2Cos(a+b)Cos(a-b)

                            =2Cos(270-c)Cos(a-b)

                           =  -2Sin(c)Cos(a-b)

 

Cos2c = 1- 2Sin22c

 

4SinaSinbSinc = 2(2SinaSinb)Sinc

                          = 2[Cos(a-b) - Cos(a+b)]Sinc

                          = 2[Cos(a-b) - Cos(270-c)]Sinc

                          = 2[cos(a-b) + Sinc]Sinc

                          = 2Cos(a-b)Sinc + 2Sin2c 

now add the results of these three parts and get the desired 

ANS = 1

 

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Hope it will help you

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