Given an isosceles triangle with length of 2 equal sides units and opposite side units with angle θ. Find the value of the angle θ opposite to the \(3\sqrt{t}\)units.

  • A 100°
  • B 120°
  • C 30°
  • D 60°
jamb 2001mathematics

The correct answer is B. 120°

Here is the given text written in MathJax:

\(\cos \theta° = \frac{t^2 + t^2 - (\sqrt{3}t)^2}{2 \times t \times t}\)

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

\(= \frac{-t^2}{2t^2}\)

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

Thus, \(\theta = \cos^{-1} (-0.5) = 120°\)

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