Question

If cos theta + sin theta = a then sin 2theta

Answer 1

sin A + cos A =a
squring both sides
(sin A +cosA)^2=a^2
sin^2A+cos^2A+2sinAcosA=a^2
1 + 2sinAcosA=a^2
2sinaAcosA=a^2-1
sin2A=a^2 -1

Answer 2

heya☺

cos¢+sin¢=a

squaring on both side first...

(cos¢+sin¢)^2=a^2

=)cos^2¢+sin^2¢+2sin¢*cos¢=a^2

=)2sin¢*cos¢=-1+a^2

=)sin2¢=a^2-1【2sin¢*cos¢=sin2】

hence ,sin2¢=a^2-1

hope it help you.

@rajukumar☺