Answer:
see explanation
Step-by-step explanation:
Using the trig identity
sin²x + cos²x = 1 , then
sin²x = 1 - cos²x
cos²x = 1 - sin²x
Consider the left side
sin²A - cos²B
= (1 - cos²A) - (1 - sin²B) ← distribute parenthesis
= 1 - cos²A - 1 + sin²B
= sin²B - cos²A
= right side , thus verified
