Given:
[tex](\text{sin}\theta+\cos \theta)^2\text{ = }\frac{5}{2}[/tex]
Let's solve for sin θ cosθ
First expand the parenthesis:
[tex]\begin{gathered} (\sin \theta+\cos \theta)^2\text{ = }\frac{5}{2} \\ \\ (\sin \theta+\cos \theta)(\sin \theta+\cos \theta)\text{ = }\frac{5}{2} \\ \\ \sin ^2\theta+\sin \theta cos\theta+\sin \theta\cos \theta+\cos ^2\theta\text{ = }\frac{5}{2} \\ We\text{ know: +}\cos ^2\theta+sin^2\theta=1 \\ ^{}\sin \theta cos\theta+\sin \theta\cos \theta\text{ +}\cos ^2\theta+sin^2\theta\text{ = }\frac{5}{2} \\ 2\sin \theta cos\theta+1\text{ = }\frac{5}{2} \end{gathered}[/tex]
[tex]\begin{gathered} \\ 2\sin \theta\cos \theta\text{ + 1 = }\frac{5}{2} \\ \\ 2\sin \theta\cos \theta\text{ = }\frac{5}{2}-1 \\ \\ 2\sin \theta\cos \theta=\text{ }\frac{3}{2} \\ \\ \sin \theta\cos \theta\text{ = }\frac{3}{2}\ast\frac{1}{2} \\ \\ \sin \theta\cos \theta\text{ = }\frac{3}{4} \\ \\ \end{gathered}[/tex]
ANSWER:
[tex]\frac{3}{4}[/tex]
