![a∈(0,2/π) ,sina=4/5,则根号3[cos(a-π/3)]等于](/img/79172117.jpg)
如题
3[cos(a-π/3)]=3cosa*1/枝伍冲2+3sina*根3/2=3/2 *(1-(sina)^2)+3根猛歼3*2/5
=3/2 *9/25+6根3/5
=(27+60根橘做3)/50
a∈(0,2/π) ,sina=4/5,则根号3[cos(a-π/3)]等于
如题
3[cos(a-π/3)]=3cosa*1/枝伍冲2+3sina*根3/2=3/2 *(1-(sina)^2)+3根猛歼3*2/5
=3/2 *9/25+6根3/5
=(27+60根橘做3)/50