Answer
$0.723 A.U.$
Work Step by Step
Step 1. Use the figure given in the problem to identify the known quantities: $\alpha=46.3^\circ$ , the distance between the Earth and the Sun $ES=1A.U.$
Step 2. In the right triangle formed by the Earth (E), Venus (V) and the Sun (S), we have $sin\alpha=\frac{VS}{ES}$
thus we have $VS=ES\cdot sin\alpha=1\times sin46.3^\circ\approx0.723 A.U.$
