For cosФ×sinФ =0, then either cosФ or sin Ф must be zero.
cos 90 = cos 270 = 0
sin 0 = sin 180 = sin 360 = 0.
So, the values that would give you 0 are:
1. cos 90 sin Ф
2. cos 270sin Ф
3. cos Ф sin 0
4. cos Ф sin 180 and
5 cos Ф sin 360.
1/4^-2 can also be written as 4^2 = 16
The set of sides that cannot be the sides of a triangle is set A.
The sum of two sides of a triangle must be longer than the third side, but 6 + 10 is less than 21, so it cannot be a triangle.
Hope this helps =)
