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.
Answer:
? = 1
Step-by-step explanation:
4/8 = ?/2
Change the ? into a variable so it's easier to calculate:
Variable x = ?
4/8 = x/2
Cross multiply:
4 × 2 = 8 × x
8 = 8x
Divide both sides by 8 to isolate the variable:
1 = x
Check your work:
4/8 = 1/2
4 × 2 = 8 × 1
8 = 8
Correct!
Answer:
300 percent change
Step-by-step explanation:
300 is 400 percent of 75.(75x4 is 300.) Therefore, the percent change is
400 - 100 = 300.
Step-by-step explanation:
Answer: Difference between five tmes a number and twelve is seven