+343 Generally its:
\(sin^2θ + cos^2θ=1 \)
so \(cosθ=\sqrt{1 - sin^2θ }=\sqrt{1 - \frac{4}{25} }=\sqrt{\frac{25}{25}-\frac{4}{25}}=\sqrt{\frac{21}{25}}=\frac{\sqrt{21}}{5}\)
+343 Generally its:
\(sin^2θ + cos^2θ=1 \)
so \(cosθ=\sqrt{1 - sin^2θ }=\sqrt{1 - \frac{4}{25} }=\sqrt{\frac{25}{25}-\frac{4}{25}}=\sqrt{\frac{21}{25}}=\frac{\sqrt{21}}{5}\)
