Answer:
[tex]\frac{\sqrt{51} }{10}[/tex]
Step-by-step explanation:
Using the Pythagorean identity
sin²x + cos²x = 1 ⇒ cosx = ± [tex]\sqrt{1-sin^2x}[/tex], hence
cosΘ = [tex]\sqrt{1-(7/10)^2}[/tex]
= [tex]\sqrt{1-\frac{49}{100} }[/tex]
= [tex]\sqrt{\frac{51}{100} }[/tex]
= [tex]\frac{\sqrt{51} }{\sqrt{100} }[/tex] = [tex]\frac{\sqrt{51} }{10}[/tex]
