Simplify (x-3)(x+ 7) using the Area model or foil, and identify the resulting expression in standard form.

x^2 +4x -21 thats the answer if you foil the expression, and it is put in standard form

∠acb = 8°

step-by-step explanation:

∠xba lies on the circle and is half the measure of the intercepted arc ax

hence

measure of arc ax = 2 × 42° = 84°

∠acb is outside the circle and is

∠acb = (arcab - arcax ), hence

∠acb = 0.5 (100 - 84) = 0.5 × 16° = 8°