Question

5sin^2a+2cos^^2a при cos^2a=0,4

Answer 1

$5sin^2a+2cos^2a=?\cos^2a=0,4\\sin^2a=1-cos^2a=1-(0,4)^2=1-0,16=0,84\\5sin^2a+2cos^2a=5*0,84+2*0,4=4,2+0,8=5$