Given sin theta = 2/5 and 0 theta 90 find sin 2 theta

Given:  sin theta = 2/5.  This tells us that the lengths of the opp side and the hyp are 2 and 5 respectively.  The adj side is found using the Pyth. Thm.:  5^2-2^2= 25-4 = 21, so that the adj side is sqrt(21).

The double angle formula for the sine is sin 2theta = 2 sin theta *cos theta.

In this particular problem, the sine of 2theta is 2*(2/5)*[sqrt(21) / 5], or:

                                                                              (4/25)*sqrt(21).

coin flip

non-answer:

choosing

sorry if this isnt what you're looking for i dont really understand the question