Which of the following is not a valid strategy for solving the given equation?
a. to solved the equation cos²θ= sinθcosθ, first subtract sinθcosθ from both sides, then factor out the common factor of cosθ on the left side. b. to solve the equation cos²θ=sinθcosθ, ***first divide both sides by cosθ.c. to solve sin2θ+2cosθsin2θ=0, first factor out the common factor of sin2θ on the left side. d. to solve the equation sinθ+cosθ=1, first square both sides of the equation.

The correct choice is B.

Step-by-step explanation:

a. Given

We can subtract from both sides to obtain;

We can then factor to obtain;

We can then proceed with our solution using the zero product principle.

b. Given , it is not valid to divide both sides by because could be equal to zero and division by zero in disguise will not result in the true solutions of the given equation.

c. To solve sin2θ+2cosθsin2θ=0, first factor out the common factor of sin2θ on the left side.

This is also a justifiable approach.

d. To solve the equation sinθ+cosθ=1, first square both sides of the equation.

Squaring both sides will help solve the equation with double angle properties easily.

30 units^2

step-by-step explanation:

area is l × w

the length is 3

and the width is 10

3 × 10= 30 units squared