WACC cost of capital

project specific cost of equity and cost of capital

business risk

financial risk

CAPM 

adjust or not depending on the change of business area( geographic ,multinational, or new industry,ways of operating....) , or gearing

same gearing, similar business  means same business and financial risk

otherwise, adjust WACC, and APV will be applied in investment project appraisal 

no gearing change: WACC for similar business

                                 adjusted WACC for different business

with gearing change(no mater similar business or new area): raising debt     APV

same industry, similar business, exist fiance to fund the new project, means the fiancial risk(gearing), the same(the pool of finance argument)