Question

The value of $\sin \Theta .\cos \Theta$ has maximum value when $\Theta$ is

• A. ${30}^{\circ }$
• B. ${45}^{\circ }$
• C. ${60}^{\circ }$
• D. ${90}^{\circ }$

Answer 1

The correct option is B ${45}^{\circ }$

$sin\theta .cos\theta =\frac{1}{2}sin2\theta$
$sin2\theta =2sin\theta .cos\theta$
Maximum value of sinA is 1 when $A={90}^{\circ }$
$2\theta ={90}^{\circ }$
$\therefore \theta ={45}^{\circ }$