Answer:
[tex]{ \rm{A .B = |A| |B| \sin( \theta) }} \\ { \rm{A.B = 5 \times 7 \times \sin(45) }} \\ { \rm{A.B = 35 \times \frac{1}{ \sqrt{2} } }} \\ \\ { \rm{A.B = \frac{35}{ \sqrt{2} } }}[/tex]
rationalise the denominator;
[tex]{ \rm{A.B = \frac{35}{ \sqrt{2} } \times \frac{ \sqrt{2} }{ \sqrt{2} } }} \\ \\ { \rm{A.B = \frac{35 \sqrt{2} }{2} }}[/tex]
