Question

1+ctgx sobre 1+tgx=ctgx

Answer 1

1+ctgx / 1+tgx = ctgx

1 + cosx/senx / 1 + senx /cosx = ctgx

(senx + cosx)/ senx / (cosx+senx)/cosx = ctgx

cosx/senx = ctgx

ctgx = ctgx