原方程变为0=-4*81(cosx)^2+900sinxcosx+10,
∴10(sinx)^2+900sinxcosx-314(cosx)^2=0,cosx≠0,
∴10(tanx)^2+900tanx-314=0,
解得tanx=-45土√205640/10,
∴x=kπ+arctan(-45土√205640/10),k∈Z.
原方程变为0=-4*81(cosx)^2+900sinxcosx+10,
∴10(sinx)^2+900sinxcosx-314(cosx)^2=0,cosx≠0,
∴10(tanx)^2+900tanx-314=0,
解得tanx=-45土√205640/10,
∴x=kπ+arctan(-45土√205640/10),k∈Z.