I need help plz ASAP

Just tell me how to set up the equation.

In δabc, m∠acb = 90°, cd ⊥ ab and m∠acd = 45°. find: a find cd, if bc = 3 in

Tom and lilly rented a house for $12,000 last year. at the start of the year they bought the house they had been renting directly from the owner for $250,000. they believe they could rent it for $12,000 this year, but stay in the house. how much does tom and lilly’s decision to buy the house change gdp? a. it reduces gdp by $12,000 b. it does not change gdp c. it raises gdp by $238,000 d. it raises gdp by $250,000