Answer the following questions related to the constant nature of certain trigonometric combinations.
a. (i) Without substituting any numerical values, explain why sin2θ+cos2θ=1 for every acute angle θ in a right-angled triangle.
b. (ii) Using your reasoning from part (i), state whether (sin230∘+cos260∘) is equal to, less than, or greater than 1. Give a brief justification.
c. (iii) Calculate the exact numerical value of (sin230∘+cos260∘) to confirm your answer in part (ii).