Q: $\displaystyle f(x) = \mathrm{arcsin} x, \ -1 \le x \le 1$.

(a)Evaluate $\displaystyle f \left( - \frac{1}{2} \right)$.

(b) Find an equation of the tangent to the curve with equation $\displaystyle y=f(x)$ at the point where $\displaystyle x = \frac{1}{\sqrt{2}}$.

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I've done part (a) but struggling with part (b). May I have some help please.