In the adjoining figure, PQR is a right triangle right angled at Q. If PQ = 4 cm and PR = 8 cm then ∠P is equal to

1. 60°

2. 45°

3. 30°

4. 15°

By formula,

cos P = $\dfrac{\text{Base}}{\text{Hypotenuse}}$

$\Rightarrow \text{cos P} = \dfrac{PQ}{PR} \\[1em] \Rightarrow \text{cos P} = \dfrac{4}{8} \\[1em] \Rightarrow \text{cos P} = \dfrac{1}{2} \\[1em] \Rightarrow \text{cos P} = \text{cos 60°} \\[1em] \Rightarrow P = 60°.$

Hence, Option 1 is the correct option.