if cosθ=3/4 with 0<θ<π/2, then determine the exact value of sin(π+θ)
cosθ = 3/4.....
sinθ = √[1 - (3/4)^2 ] =√[ 1 - 9/16] = √ [7] / 4
sin( pi + θ) = sin(pi)cosθ + cos pi sin θ = 0 + ( - √ [7] / 4 ) = - √ [7] / 4
+140 
