Answer:cos( A + B ) = cosAcosB - sinAsinB ;
cos( A + B ) / ( cosAsinB ) = ( cosAcosB - sinAsinB ) / ( cosAsinB ) = ( cosAcosB ) / ( cosAsinB ) - ( sinAsinB ) / ( cosAsinB ) = cosB / sinB - sinA / cosA = cotB - tanA ;
tan²(x) - sin²(x) = sin²(x)/cos²(x) - sin²(x)
… = sin²(x) (1/cos²(x) - 1)
… = sin²(x) (sec²(x) - 1)
… = sin²(x) tan²(x)
Step-by-step explanation:
