sin(90+a)-cos(a-90)^2*1/sin(a+90) если a=-1 (упростите выражение)

$$sin{left (a + 90 right )} – frac{cos^{2}{left (a – 90 right )}}{sin{left (a + 90 right )}}$$

$$sin{left (a + 90 right )} – frac{cos^{2}{left (a – 90 right )}}{sin{left (a + 90 right )}}$$

sin(90 + (-1)) – cos((-1) – 90)^2/sin((-1) + 90)

$$sin{left ((-1) + 90 right )} – frac{cos^{2}{left ((-1) – 90 right )}}{sin{left ((-1) + 90 right )}}$$

sin(90 – 1) – cos(-1 – 90)^2/sin(-1 + 90)

$$- frac{cos^{2}{left (-90 – 1 right )}}{sin{left (-1 + 90 right )}} + sin{left (-1 + 90 right )}$$

-cos(91)^2/sin(89) + sin(89)

$$- frac{cos^{2}{left (91 right )}}{sin{left (89 right )}} + sin{left (89 right )}$$

-cos(a – 90)^2/sin(a + 90) + sin(90 + a)

$$frac{1}{sin{left (a + 90 right )}} left(sin^{2}{left (a + 90 right )} – cos^{2}{left (a – 90 right )}right)$$

$$frac{1}{sin{left (a + 90 right )}} left(sin^{2}{left (a + 90 right )} – cos^{2}{left (a – 90 right )}right)$$

$$- left(frac{1}{2} cos{left (2 a – 180 right )} + frac{1}{2}right) csc{left (a + 90 right )} + sin{left (a + 90 right )}$$

-(-sin(90 + a) + cos(-90 + a))*(cos(-90 + a) + sin(90 + a))
————————————————————
sin(90 + a)

$$- frac{1}{sin{left (a + 90 right )}} left(- sin{left (a + 90 right )} + cos{left (a – 90 right )}right) left(sin{left (a + 90 right )} + cos{left (a – 90 right )}right)$$

2
(cos(90)*cos(a) + sin(90)*sin(a))
cos(90)*sin(a) + cos(a)*sin(90) – ———————————-
cos(90)*sin(a) + cos(a)*sin(90)

$$- frac{left(sin{left (90 right )} sin{left (a right )} + cos{left (90 right )} cos{left (a right )}right)^{2}}{sin{left (a right )} cos{left (90 right )} + sin{left (90 right )} cos{left (a right )}} + sin{left (a right )} cos{left (90 right )} + sin{left (90 right )} cos{left (a right )}$$