Answer:
-5x + 8y = -21
3x - 4y = 15
8y = 5x - 21
y = 5/8x - 21/8
3x - 4y = 15
-4y = -3x + 15
y = 3/4x - 15/4
5/8x - 21/8 = 3/4x - 15/4
-1/8x = -9/8x
x = 9
3x - 4y = 15
3(9) - 4y = 15
27 - 4y = 15
-4y = -12
y = 3
(9, 3)
Okay. 400cm is 4 meters. The ration of 4 meters : 2 meters simplified is 2 meters : 1 meter. The ration is 2 meters : 1 meter (200 cm : 1 meter).
Cos2x = (cosx)^2 - (sinx)^2;
sin2x = 2sinxcosx;
Then, (2cos2x)/(sin2x) =2[ (cosx)^2 - (sinx)^2 ] / (2sinxcosx) = [ (cosx)^2 - (sinx)^2 ] / (sinxcosx) = (cosx)^2 / (sinxcosx) - (sinx)^2 / (sinxcosx) = cosx/sinx - sinx/cosx = cotx - tanx;
