transform the first expression into the second. sin t tan t cos t, cos t sin t' 1-sin t sin t cos t 1- cos t sin t tan t sin t + cost, 1 cos t 1-cos t cos't cos t 1-sin t' use trigonometric identities to 1 tan t 1 1-sin cos t tant cos t sin t tan t 1 + sin t 1 COS ! (sin t - cos t), 1-2 sint cos t 1+ sin t' sin t 2 cos