of the area of the circle. \(A = \frac{135}{360} \times π \times 4^2\) \(A = 18.85 (2 d.p.)\) Calculate the perimeter of the sector. The perimeter is made up of an arc and two straight sides.

THIS book treats of the difficult problem of girders forming a circular arc in plan such as are often used to support the balcony of a theatre. The principles on which the general problem may be ...