Find the value of theta in the diagram - JAMB Mathematics 2001 Question

Using cosine formula (t(\sqrt{3}))² = t² + t² - 2t² cos(\theta)

3t² = 2t² - 2t² cos(\theta) = 2t²(1 - cos(\theta))

1 - cos(\theta) = (\frac{3t^2}{2t^2}) = (\frac{3}{2})

cos = 1 - (\frac{3}{2} = -\frac{1}{2})

(\theta) = cos^-1(-(\frac{1}{2})) = 120^o and 240^o

N.B 0 (\geq) (\theta) 360