题目内容
sinA- 1<0
①sin30°+sin30°=sin60° ②若cosA=sinB，则ÐA=ÐB ③若cosA=sin30°，则锐角A=60° ④sin60°+cos60°=2(sin30°+cos30°)
A．0 B．1 C．2 D．3
A．0°<ÐA<30° B．30°<ÐA<45°
C．45°<ÐA<60° D．60°<ÐA<75°
=________.
=________.
=________.
