Answer:
Step-by-step explanation:
cos x cos (3x)+sinx sin (3x)=0
cos (x-3x)=0
cos(-2x)=0
cos 2x=0=cos (2n+1)π/2
where n=0,1,2,3∞∞∞∞
2x=(2n+1)π/2
x=(2n+1)π/4
put n=0,1,2,3
x=π/4,3π/4,5π/4,7π/4
The <em>correct answer</em> is:
2 pieces, with 1/12 m left over.
Explanation:
To find the number of 1/3 meter pieces she can cut from a 3/4 meter ribbon, we divide:
3/4÷1/3
To divide fractions, flip the second one and multiply:
3/4×3/1
To multiply fractions, multiply straight across:
(3*3)/(4*1) = 9/4
4 will go into 9 two times with 1 left over, so this simplifies to 2 1/4; this means she can cut 2 pieces this length.
2 pieces that are 1/3 meter long is a total of 2(1/3) = 2/3 m. To find out how much is left, subtract:
3/4 - 2/3
Common denominator is 12:
3/4 = 9/12 and 2/3 = 8/12
9/12 - 8/12 = 1/12
There is 1/12 of a meter left.
