Question

已知α为第二象限角,化简sinα/cosα *根号下[1/sin^2α -1]

Answer 1

α为第二象限角
sinα/cosα *根号下[1/sin^2α -1]
=sinα/cosα *根号下[(1-sin^2α)/sin^2α]
=sinα/cosα *根号下[cos^2α)/sin^2α]
=sinα/cosα *(-cosα)/(sinα)
=-1