+0

# Two questions ...

+3
546
3
+1832

Aug 16, 2014

### Best Answer

#3
+121078
+13

Yes, xvxvxv, e is correct for the second question.

As to your hypothesis...let's see if this it is true that cos(n*pi + x) = cos(x)

Using a trig identity, we have

cos(n*pi + x) =

cos(n*pi)cos(x) - sin(n*pi)sinx  =

cos(n*pi)cos(x)

Notice that this equals cos(x) only when n = 0, 2, 4, 6......

Aug 16, 2014

### 3+0 Answers

#1
+32822
+13

Alan Aug 16, 2014
#2
+1832
+3

nice alan .. so question 2 the answer is e ! right ?

and I want to ask ... from your amswer in question 6 I Concluded this law                                                                   cos(npi + x ) = cos(x)    ...  n mean any Integer number ( 0 , 1 , 2 , 3 ....... )

Aug 16, 2014
#3
+121078
+13
Best Answer

Yes, xvxvxv, e is correct for the second question.

As to your hypothesis...let's see if this it is true that cos(n*pi + x) = cos(x)

Using a trig identity, we have

cos(n*pi + x) =

cos(n*pi)cos(x) - sin(n*pi)sinx  =

cos(n*pi)cos(x)

Notice that this equals cos(x) only when n = 0, 2, 4, 6......

CPhill Aug 16, 2014