Let θ be an angle such that cosθ=−23 and 180∘<θ<360∘.
a. (i) Identify the possible quadrants in which θ can lie and state the corresponding sign of sinθ in each.
b. (ii) Determine the correct value of sinθ.
c. (iii) Write the least positive value of θ satisfying the given condition in both degree and radian measure.
d. (iv) Using the obtained values of sinθ and cosθ, show that sin2θ+cos2θ=1.