Answer:
Step-by-step explanation:
sec(2a+6)cos (5a+3)=1
[tex]\frac{cos(5a+3)}{cos(2a+6)} =1\\[/tex]
cos(5a+3)=cos(2a+6)
cos(5a+3)-cos(2a+6)=0
[tex]-2sin(\frac{5a+3+2a+6)}{2} )sin(\frac{5a+3-2a-6)}{2} )=0\\-2sin(\frac{7a+9}{2} )sin(\frac{3a-3}{2} )=0\\either sin (\frac{7a+9}{2} )=0=sin ~n\pi \\\frac{7a+9}{2} =n~\pi \\7a+9=2n~\pi \\7a=2n~\pi -9\\a=\frac{2n\pi-9 }{7} \\where~n~is~an~integer.[/tex]
or
[tex]\sin\frac{3a-3}{2} =0=\sin ~n\pi \\3a-3=2n\pi \\3a=2n\pi+3\\a=\frac{2~n\pi+3 }{3}[/tex]
where n is an integer.
