Find the radius of the arc?
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A door with a width $4.20$ m has an arc as shown in the diagram. Find:
a) the radius of the arc, to the nearest cm
b) the length of the arc, to the nearest cm.
I need help in part a). For b), we can use the formula $L=r \theta$. You can see the picture in the link.
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The radius
$$ R= \dfrac{ 2.1}{\sin 67.5^{\circ}}$$$$ Arc= R\; 3 \pi/4. $$
