最简三角方程tan7x=-tan3x cos5x=-cosx

网友回答

tan7x=-tan3x ==>tan7x=tan(π-3x)==>7x=kπ+π-3x==>10x=(k+1)π==>x=(k+1)π/10,k∈Z
cos5x=-cosx ==>cos5x=cos(π-x)==>5x=2kπ±(π-x)
==>5x±x=(2k±1)π==>x=(2k±1)π/6或x=(2k±1)π/4,k∈Z