Question

Please help me with this

Answer 1

Answer:

$\frac{\sqrt{51} }{10}$

Step-by-step explanation:

Using the Pythagorean identity

sin²x + cos²x = 1 ⇒ cosx = ± $\sqrt{1-sin^2x}$, hence

cosΘ = $\sqrt{1-(7/10)^2}$

        = $\sqrt{1-\frac{49}{100} }$

        = $\sqrt{\frac{51}{100} }$

        = $\frac{\sqrt{51} }{\sqrt{100} }$ = $\frac{\sqrt{51} }{10}$