What is the value of c such that x^2 — 12x + c is a perfect-square trinomial?

40 & 50 in the right corner are the complementary angles as when placed in a sum (added together) they make 90°

This is what i found “an explicit formula designates the nth term of the sequence, as an expression of n (where n = the term's location). it defines the sequence as a formula in terms of n. this example is an arithmetic sequence(the same number, 5, is added to each term to get to the next term).” i hope this you for what your looking for. can you plz mark me brainliest?