Let cheese wafers = x
chocolate wafers = y
we know they bought 20 total packets so x+y = 20, this can be re-written as x = 20-y
cheese wafers cost 2, so we have 2x
chocolate wafers cost 1, so we have 1y, which is just the letter y
so we know 2x + y = $25
replace x with x=20-y to get:
2(20-y)+y = 25
distribute the parenthesis:
40-2y +y = 25
combine like to terms to get:
40-y = 25
subtract 40 from each side"
-y = -15
divide both sides by -1
y = 15
chocolate wafers was y so they bought 15 chocolate wafers
cheese wafers was x, so they bought 20-15 = 5 cheese wafers
using the substitution method was the easiest way to isolate one of the variables in order to find the solution.
Answer:
210
Step-by-step explanation:
We know that
2π/3 radians-------> convert to degrees-----> 2*180/3---> 120°
120°=90°+30°
Part a) Find <span>sin(2π/3)
</span>sin(2π/3)=sin (90°+30°)
we know that
sin (A+B)=sin A*cos B+cos A*sin B
so
sin (90°+30°)=sin 90*cos 30+cos 90*sin 30
sin 90=1
cos 30=√3/2
cos 90=0
sin 30=1/2
sin (90°+30°)=1*√3/2+0*1/2-----> √3/2
the answer part a) is
sin(2π/3)=√3/2
Part b) Find cos (2π/3)
cos (2π/3)=cos (90°+30°)
we know that
cos (A+B)=cos A*cos B-sin A*sin B
so
cos (90°+30°)=cos 90*cos 30-sin 90*sin 30
sin 90=1
cos 30=√3/2
cos 90=0
sin 30=1/2
cos (90°+30°)=0*√3/2-1*1/2----> -1/2
the answer part b) is
cos (2π/3)=-1/2
Answer:
The sequence is:
10, 30, 50, 70, 90.....................
Step-by-step explanation:
We have,
First term (a) = 10
Common difference (d) = ?
Sum of first 5 terms (
) = 250
or, ![\frac{n}{2} [{2a+(n-1)d}] = 250](https://tex.z-dn.net/?f=%5Cfrac%7Bn%7D%7B2%7D%20%5B%7B2a%2B%28n-1%29d%7D%5D%20%3D%20250)
or, ![\frac{5}{2} [2*10 + 4d]=250](https://tex.z-dn.net/?f=%5Cfrac%7B5%7D%7B2%7D%20%5B2%2A10%20%2B%204d%5D%3D250)
or, ![\frac{5}{2} * 4[5+d]=250](https://tex.z-dn.net/?f=%5Cfrac%7B5%7D%7B2%7D%20%2A%204%5B5%2Bd%5D%3D250)
or, 10(5 + d) =250
or, 5 + d = 25
∴ d = 20
Now,
2nd term = a + d = 10 + 20 = 30
3rd term = a + 2d = 10 + 2*20 = 10 + 40 = 50
4th term = a + 3d = 10 + 3*20 = 10 + 60 = 70
5th term = a + 4d = 10 + 4*20 = 10 + 80 = 90