In the right triangle ABC, C is equal to 90 degrees, AC is equal to twice BC, then the value of sina is?

In the right triangle ABC, C is equal to 90 degrees, AC is equal to twice BC, then the value of sina is?

Using Pythagorean theorem to find the hypotenuse,

In △ ABC, ∠ C = 90 °, BC = 4, Sina = 2 / 3, then the length of AC is__ .

Because in △ ABC, ∠ C = 90 °, BC = 4, Sina = 2 / 3,
So Sina = BC / AB = 4 / AB = 2 / 3, so AB = 6, so AC = radical (the square of 6 - the square of 4) = 2 * radical 5

As shown in the figure, the side length of equilateral △ ABC is 12, ad is the middle line on BC side, M is the moving point on ad, e is a point on AC side, if AE = 4, the minimum value of EM + cm is______ ．

Take the midpoint F of CE and connect DF. ∵ equilateral △ ABC has side length of 12, AE = 4, ∵ CE = ac-ae = 12-4 = 8, ∵ CF = EF = AE = 4, ad is the midline on the edge of BC, ∵ DF is the median line of △ BCE, ∵ be = 2DF, be ∥ DF, e is the midpoint of AF, ∵ m is the midpoint of AD, ∵ me is the median line of △ ADF,