Cost of Capital: r = D/P + g

Rearrange the growing perpetuity to isolate $r$, name $D/P_t$ the dividend yield, and record that the required return is current payout plus growth, not dividend yield alone.

State the ex-dividend timing convention, rewrite the formula with the last dividend $D_0$, note that $g$ must match the payment cycle, and estimate one company's cost of capital numerically.

Record that $P=D/r$ makes nearly every stock look overpriced by omitting $g$, and that the formula ties $r$ and $g$ together without pinning down either alone.

Record that $D$ is the steady-state dividend, the historical substitution of earnings, the perverse result for negative cash flows, and the need to model non-steady-state periods explicitly.