P.o.t.W. #10
■ No GDC ■ for SL and HL students Consider an isosceles triangle with the characteristics shown in the figure below where the angle marked \(\theta is between the two equal sides of length \(x , and opposite the side of length \(a . Find two different methods (ways) to show that \(\cos \left( {\frac{\theta }{2}} \right) = \sqrt {1 - \frac{{{a^2}}}{{4{x^2}}}} . PDF: P.o.t.W. #10