Jambmaths question:
In a triangle PQR, q =8cm,r = 6cm and$\cos P=\tfrac{1}{12}$. Calculate the value of p
Option A:
9cm
Option B:
$\sqrt{92}cm$
Option C:
10cm
Option D:
$\sqrt{108}cm$
Jamb Maths Solution:
$\begin{align} & \text{using cosine rule } \\ & {{p}^{2}}={{r}^{2}}+{{q}^{2}}-2rq\cos P \\ & {{p}^{2}}={{6}^{2}}+{{8}^{2}}-2(6)(8)(\tfrac{1}{12}) \\ & {{p}^{2}}=100-8 \\ & p=\sqrt{92}cm \\\end{align}$
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