5.) write the trigonometric function sin 64° in terms of its co-function.
a) cos (64°)
b) cos (116°)
c) cos (26°)
d) cos (46°)

So...sin (90-theta) = cos theta

so sin 64= sin(90-26)
=>cos 26

so the answer is C

Cos(26)

because

Sin(x) = Cos(90 - x)
and
Cos(x) = Sin(90 - x)

1. 0.3 •4 is the same as 4 groups of 0.32. 7•0.8 is the same as 7 groups of 0.83. it increases by 0.5 every time, so 0.5x4 it increases by 0.9 every time, so 0.9x5. 0.9•12=10.86. 0.47•5=2.35i can finish the next ones in a separate post