8*cos(2*a)^2-4*cos(4*a)+7 если a=-1/4 (упростите выражение)

$$8 cos^{2}{left (2 a right )} – 4 cos{left (4 a right )} + 7$$

$$8 cos^{2}{left (2 a right )} – 4 cos{left (4 a right )} + 7$$

8*cos(2*(-1/4))^2 – 4*cos(4*(-1/4)) + 7

$$8 cos^{2}{left (2 (-1/4) right )} – 4 cos{left (4 (-1/4) right )} + 7$$

8*cos(2*(-1)/4)^2 – 4*cos(4*(-1)/4) + 7

$$- 4 cos{left (frac{-4}{4} right )} + 8 cos^{2}{left (frac{-2}{4} right )} + 7$$

7 – 4*cos(1) + 8*cos(1/2)^2

$$- 4 cos{left (1 right )} + 8 cos^{2}{left (frac{1}{2} right )} + 7$$

7.0 + 8.0*cos(2*a)^2 – 4.0*cos(4*a)

11

$$11$$

$$11$$

11

$$11$$

2
4 4 / 2 2 2 2
7 – 4*cos (a) – 4*sin (a) + 8*cos (a) – sin (a)/ + 24*cos (a)*sin (a)

$$8 left(- sin^{2}{left (a right )} + cos^{2}{left (a right )}right)^{2} – 4 sin^{4}{left (a right )} + 24 sin^{2}{left (a right )} cos^{2}{left (a right )} – 4 cos^{4}{left (a right )} + 7$$