Asked by AA
given that sinx, tanx, and sin2x form geometric sequence, show cos^3x=1/2
can someone explain this to me, i have no idea how to solve it. i really done understand how to turn it into a geometric sequence
can someone explain this to me, i have no idea how to solve it. i really done understand how to turn it into a geometric sequence
Answers
Answered by
Steve
just think back to your Algebra II. Terms of a GP have a common ratio, so
tanx/sinx = sin2x/tanx
1/cosx = = 2sinx*cosx * cosx/sinx
...
tanx/sinx = sin2x/tanx
1/cosx = = 2sinx*cosx * cosx/sinx
...