Answer: i added a pic of the answers
Step-by-step explanation:
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
Cos A) 16/20 or 4/5
Tan A) 12/16 or 3/4
Sin A) 12/20 or 3/5
Answer:
27.8
Step-by-step explanation:
You need to do brackets first
3.6-1.8 = 1.8
Then substitute
4.5 x 8- (0.4 + 9.6- 1.8)
0.4+9.6-1.8=8.2
4.5 x 8 - 8.2 =27.8
The shape has five edges (if your including the point at the top) and five faces
