Prove: sinx-2sin3x+sin5x=2sinx(cos4x-cos2x )

A = sinx - sin3x,  

B = -sin3x + sin5x  

First A:  

The average of x and 3x is 2x, and they (x and 3x, that is) are each a distance of x from this average. That's fancy talk for:  

x = 2x-x,  

3x = 2x+x.  

So, A = sin(2x-x) - sin(2x+x)  

Using angle sum formulas:  

A = (sin2x cosx - cos2x sinx) - (sin2x cosx + cos2x sinx)  

A = -2 cos2x sinx  

Similarly,  

B = -sin(4x-x) + sin(4x+x)  

= -(sin4x cosx - cos4x sinx) + (sin4x cosx + cos4x sinx)  

B = 2 cos4x sinx  

Now,  

sinx - 2sin3x + sin5x = A+B = -2 cos2x sinx + 2 cos4x sinx  

= 2 sinx (cos4x - cos2x).  

answer: given that the roller coaster can accommodate 1600 riders per hour, thus the roller coaster can accomodate 1600 / 60 = 26.67 riders per minute.

given that there are 345 people in the line, the number of minutes it will take for the 345 persons to get into the roller coaster is given by 345 / 26.67 = 12.94 minutes.

therefore, it will take you 12.94 minutes to get to the front of the line.

step-by-step explanation:

7 weeks

step-by-step explanation:

convert each fraction to the least common multiple of 20, so 3/4 = 15/20 & 1/10 = 2/20, then divide 15 by 2 and you get a little over 7, so the food will last 7 weeks.