七点到八点之间什么时间,分针和时针的夹角90度?
(30×7-90)÷(6-0.5)
=(210-90)÷5.5
=120÷5.5
=240/11
=21又9/11分
(30×7+90)÷(6-0.5)
=(210+90)÷5.5
=300÷5.5
=600/11
=54又6/11分
7点21又9/11分或7点...
七点到八点之间什么时间,分针和时针的夹角90度?
(30×7-90)÷(6-0.5)
=(210-90)÷5.5
=120÷5.5
=240/11
=21又9/11分
(30×7+90)÷(6-0.5)
=(210+90)÷5.5
=300÷5.5
=600/11
=54又6/11分
7点21又9/11分或7点...