•2/7 + 3/7= 5/7
•4/13 + 8/13= 12/13
•5/19 + 4/19 = 9/19
•20/23 + 1/23 = 21/23
Удачи.
sin^2=1-cos^2
sin^2=1-0.6^2=1-0.36=0.64
sin a = 0.8
tg =sin/cos =0.8/0.6= 4/3 =1.3333
1) (1/4)^(-1/2) = 3x+3
2=3x+3
x= -1/3
2)(1/2)^-3 = 4-4x
8=4-4x
x=-1
3) (1/3)^(-1/2)= x-4
√3= x-4
x= 4+√3
как то так.....надеюсь помогла.....