Answer:
Step-by-step explanation:
Use the half angle identity for cosine:
cos(x/2)=+ or - sqrt(1+cos(x))/sqrt(2)
I'm going to figure out the sign part first for cos(x/2)...
so x is in third quadrant which puts x between 180 and 270
if we half x, x/2 this puts us between 90 and 135 (that's the second quadrant)
cosine is negative in the second quadrant
so we know that
cos(x/2)=-sqrt(1+cos(x))/sqrt(2)
Now we need cos(x)... since we are in the third quadrant cos(x) is negative...
If you draw a reference triangle sin(x)=3/5 you should see that cos(x)=4/5 ... but again cos(x)=-4/5 since we are in the third quadrant.
So let's plug it in:
cos(x/2)=-sqrt(1+4/5)/sqrt(2)
No one likes compound fractions (mini-fractions inside bigger fractions)
Multiply top and bottom inside the square roots by 5.
cos(x/2)=-sqrt(5+4)/sqrt(10)
cos(x/2)=-sqrt(9)/sqrt(10)
cos(x/2)=-3/sqrt(10)
Rationalize the denominator
cos(x/2)=-3sqrt(10)/10
Answer:
15.33cm
Step-by-step explanation:
when you try to draw out this figure, satisfying the fact that Ad and Ac are both straight lines. you find the ultimately it forms a right-angled triangle with sides AC and AD and hypotenuse CD.
Now, you may use Pythagoras theorem to solve:
AC^2 + AD^2 = CD^2
12.3^2 + 9.15^2 = CD^2
CD^2 = 235.0125
CD = square root of 235.0125 = 15.33cm
Hope this helps
Answer:
36
Step-by-step explanation:
12 x 3 =36
Answer:
She can ride 17.045 Miles in one hour.
Step-by-step explanation:
(250 feet/10 seconds) x (1 mile/5280 feet) x (60 seconds/ 1 minute) x (60 minutes/ 1 hour) = 17.045 Miles per hour
Answer:
Step-by-step explanation:
The associative property states that you can add or multiply regardless of how the numbers are grouped.
