Question

求函数y=﹙sin²α－5sinα+7﹚／﹙3－sinα﹚的值域

Answer 1

y=[(sinα)^2-5sinα+7]/(3-sinα)

=[(3-sinα)^2-(3-sinα)+1]/(3-sinα)

=(3-sinα)+1/(3-sinα)-1

2