Roof angle

The house's roof has the shape of an isosceles triangle with arms 4 m long and the size of the base 6 m. How big an angle alpha does its roof make?

Correct answer:

A =  41.4096 °

Step-by-step explanation:

$$\begin{gathered} r=4\text{m} \\ z=6\text{m} \\ a=z/2=6/2=3\text{m} \\ \cos A=a:r \\ A=\frac{180°}{\pi }\cdot \arccos (a/r)=\frac{180°}{\pi }\cdot \arccos (3/4)=41.4096^{\circ }=41°24^{\prime }35" \end{gathered}$$

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