$18 haircut; 10% discount work it out
2 answers:
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I'll assume that what was meant was 
.
The exponent in the funny place is just an abbreviation:
.
I hope that's what you meant. Let me know if I'm wrong.
Let's start from the old saw
Squaring both sides,
So now the original question
becomes
Now we use the sine double angle formula
We square it to see
Taking the square root,
Not sure how you want it; we'll do it in degrees.
When we know the sine of an angle, there's usually two angles on the unit circle that have that sine. They're supplementary angles which add to
. But when the sine is 1 or -1 like it is here, we're looking at 
and 
, which are essentially their own supplements, slightly less messy.
That means we have two equations:
integer 
or
We can combine those for a final answer,
integer
Check. Let's just check one, how about
The exponent in the funny place is just an abbreviation:
I hope that's what you meant. Let me know if I'm wrong.
Let's start from the old saw
Squaring both sides,
So now the original question
becomes
Now we use the sine double angle formula
We square it to see
Taking the square root,
Not sure how you want it; we'll do it in degrees.
When we know the sine of an angle, there's usually two angles on the unit circle that have that sine. They're supplementary angles which add to
That means we have two equations:
or
We can combine those for a final answer,
Check. Let's just check one, how about