Answer:
AB = 7
Step-by-step explanation:
Using the cosine ratio in the right triangle and the exact value
• cos45° = [tex]\frac{1}{\sqrt{2} }[/tex] , then
cos45° = [tex]\frac{adjacent}{hypotenuse}[/tex] = [tex]\frac{AB}{AC}[/tex] = [tex]\frac{AB}{7\sqrt{2} }[/tex] = [tex]\frac{1}{\sqrt{2} }[/tex] ( cross multiply )
AB × [tex]\sqrt{2}[/tex] = 7[tex]\sqrt{2}[/tex] ( divide both sides by [tex]\sqrt{2}[/tex] )
AB = 7
