You can solve both by LH rule ... but lets try a different tune. First problem xa (sin-1x - sin-1a) / (x - a) =( - )/(sin - sin ) where sin-1x = and sin-1a = =( - )/2cos[( +)/2]sin[( -)/2] =(( - )/2)/sin[( -)/2] x (2/cos[( +)/2]) =1 x 2 =2
Second problem x/6 sin (x - /6) / 3 - 2cos x =x/6 sin (x - /6) / 2( 3/2 - cos x) =x/6 sin (x - /6) / 2(cos/6 - cos x) = x/6 2sin [(x - /6)/2] cos[(x - /6)/2]/ 4sin [(x + /6)/2]sin [(x - /6)/2] =x/6 (1/2)[cos[(x - /6)/2]/sin [(x + /6)/2]] =(1/2) x 1 / (1/2) = 1