In triangle $ABC$ below, $AB = x$ cm, $BC = y$ cm, $AC = 14$ cm and angle \(\angle ABC = 120

Question

In triangle $ABC$ below, $AB = x$ cm, $BC = y$ cm, $AC = 14$ cm and angle $\angle ABC = 120{}^\circ$. Using cosine rule, form an equation involving $x$ and $y$.[1] Given that the perimeter of triangle $ABC$ is $30$ cm, find the exact area of triangle $ABC$.[4]

Accepted Answer

(a) $196=x^2+y^2+xy$ (b) $15\sqrt3\text{ cm}^2$

(A Math) 2025 CCHY PRELIMS P1 Q4

(A Math) 2025 CCHY PRELIMS P1 Q4

Solution:

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