SOLUTION: Hello, i'm having trouble on starting this identity. cos(x-(3pi/2))+cos(x-(3pi/2)) = 0 i have already plugged in a value to see if it is a real identity and it is. please

Algebra ->  Trigonometry-basics -> SOLUTION: Hello, i'm having trouble on starting this identity. cos(x-(3pi/2))+cos(x-(3pi/2)) = 0 i have already plugged in a value to see if it is a real identity and it is. please      Log On


   

Question 768931: Hello, i'm having trouble on starting this identity.
cos(x-(3pi/2))+cos(x-(3pi/2)) = 0
i have already plugged in a value to see if it is a real identity and it is.
please help. thank you.
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

since cos%28x-%283pi%2F2%29%29+=+-sin%28x%29+, we have
cos%28x-%283pi%2F2%29%29+%2Bcos%28x-%283pi%2F2%29%29+=+-2+sin%28x%29

and -2+sin%28x%29=+0 for all x+=+pi%2A+n, where +n element Z
since sin%28pi%29=0 we can use any number n, result will be 0
for example if n=1, then sin%28pi%29+=+0, as sin%282pi%29=0 as well, and so on