(1+sqrt(6))^2=1+2sqrt(6)+6=7+2sqrt(6)
Tg(a + π/4) = (tga + 1) / (1 - tga) = 0.2
0.2*(1 - tga) = tga + 1
0.2 - 0.2tga = tga + 1
-0.8 = 1.2tga
tga = -0.8/1.2
ctga = 1/tga = -1.2/0.8 = 1.5
2³⁰:8⁹=2³⁰:(2³)⁹=2³⁰:2²⁷=2³⁰⁻²⁷=2³=8
Можно подругому
2³⁰:8⁹=(2³)¹⁰:8⁹=8¹⁰:8⁹=8¹⁰⁻⁹=8