Question

Find all solutions in the interval [0, 2pi).

(sin x) (cos x) = 0

Answer 1

set each factor equal to zero and solve
sinx=0 cosx=0

Answer 2

I'm still confused :/

Answer 3

do you have a trig table

Answer 4

http://www.google.com/imgres?imgurl=http://jwbales.us/precal/part4/part4.3_files/image002.gif&imgrefurl=http://jwbales.us/precal/part4/part4.3.html&h=288&w=499&sz=4&tbnid=lAWt_pAYidchNM:&tbnh=66&tbnw=115&prev=/search%3Fq%3Dtrig%2Btable%2Bof%2Bvalues%26tbm%3Disch%26tbo%3Du&zoom=1&q=trig+table+of+values&usg=__miMHeXxLCkq9a5WLv6O6aEYv-xM=&docid=D_jB4Igwoq7lhM&hl=en&sa=X&ei=6MPTUNf4IILs2gWv94CIAw&ved=0CDcQ9QEwAg&dur=7165

Answer 5

if you look at the graph of sine, it is wherever x crosses the x axis

Answer 6

http://www.purplemath.com/modules/triggrph.htm

Answer 7

this is the sine graph, it crosses 0 in three places

Answer 8

So, basically, if you have two numbers, x and y, for the product, x * y, to be zero, either x must be zero or y must be zero. He's just saying, find out where sin(x) is zero and where cos(x) is zero, and that's your solution.

Alternatively, and this is just over-complicating it for this problem, sinx*cosx = (1/2)sin(2x), so you can also just solve for where sin(2x) is 0 => 2x = 0 or 2x = pi and solve for x.

Answer 9

those 3 places are your solutions