If cost 910 where pi Solutioncos t 910 sin t sqrt 19 1

Solution

cos t = -9/10

sin t = - sqrt 19 / 10

cos 2t = cos^2 t - sin^2 t

= (-9/10 )^2 - (- sqrt 19 / 10 )^2

= 81 / 100 - 19 / 100

= 62/100

= 31/50

sin (2t ) = 2 sin t cos t

= 2 ( - sqrt 19 / 10 ) ( -9/10)

= 18 sqrt 19 / 100

= 9 sqrt 19 / 50

cos (t/2) = - sqrt ( 1 + cos t ) /2

= - sqrt ( 1 - 9/10) /2

= - sqrt ( 1/20 )

= - sqrt 5 / 10

sin (t/2 ) = - sqrt ( 1- cos t ) /2

= sqrt ( 1 + 9/10) /2

= sqrt 95 / 10