sinθ = 0.7 then cosθ, 0 ≤ θ < 90° is?

Answer: Option C

$$\begin{array}{rl}& \sin \theta =0.7\\ & \Rightarrow {\sin }^2\theta +\text{co}{\text{s}}^2\theta =1\\ & \Rightarrow {\left(0.7\right)}^2+\text{co}{\text{s}}^2\theta =1\\ & \Rightarrow 0.49+\text{co}{\text{s}}^2\theta =1\\ & \Rightarrow \text{co}{\text{s}}^2\theta =1-0.49\\ & \Rightarrow \text{cos}\theta =\sqrt{0.51}\end{array}$$