Solve these trigonometric equations

a) sin^-1 (2x) = - π/6

b) 5cos^-1 (x) = 2 π

and using General Solution:

a) cosec (x) = 2

b) 3sec(4x) = 10

THANKS BEST ANSWERS PLEASE <3

a) x = ( 1 / 2 ) sin ( π / 6 ; b) x = cos ( 2π / 5 )

a) sin x = 1 / 2 ---> x = π / 6 + 2 k π , 5π / 6 + 2kπ
b) cos (4x) = 0.3 ----> 4x = ± 1.2661 + 2nπ ---> x = ± 0.3155 + nπ / 2