the answer for the question is b! :)
is there any answers or no?
2.5= 2 1/2
just do 10/20= .5 so 7.5
8.2= 8 2/10 which simplifies to 8 1/5
2.88=2 <span>22/<span>25
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3/6= 7.5
3 1/4= 3.25
i couldn't see the other ones except for also 12
2.1= 2 1/10
Use the double angle identity:
sin(2<em>x</em>) = 2 sin(<em>x</em>) cos(<em>x</em>)
Now rewrite
sin(2<em>x</em>) sin(<em>x</em>) + cos(<em>x</em>) = 0
as
2 sin²(<em>x</em>) cos(<em>x</em>) + cos(<em>x</em>) = 0
Factor out cos(<em>x</em>) :
cos(<em>x</em>) (2 sin²(<em>x</em>) + 1) = 0
Consider the two cases,
cos(<em>x</em>) = 0 OR 2 sin²(<em>x</em>) + 1 = 0
Solve for cos(<em>x</em>) and sin²(<em>x</em>) :
cos(<em>x</em>) = 0 OR sin²(<em>x</em>) = -1/2
Squaring a real number always gives a non-negative number, so the second case doesn't offer any real solutions. We're left with
cos(<em>x</em>) = 0
Cosine is zero for odd multiples of <em>π</em>/2, so we have
<em>x</em> = (2<em>n</em> + 1) <em>π</em>/2
where <em>n</em> is any integer.