A river flows West → East, then turns left and follows a semicircular path around a hillock, and then turns left by a right angle (90°). In which direction is the river finally flowing?

Introduction / Context:This question involves successive left turns along curved and straight segments. We must track heading changes qualitatively: starting flow East, a left deflection, then a continuing left semicircle (180° of turning), and finally another left 90°.

Given Data / Assumptions:

• Initial heading: East.
• Left turn into a semicircle around a hill (continuous left curvature totaling 180°).
• After completing that semicircle, there is an additional discrete left turn of 90°.

Concept / Approach:Model headings cumulatively. A left semicircle means “continue turning left until you have turned through 180° from the entry heading.” Keep careful track of the orientation at entry and exit of the curved segment.

Step-by-Step Solution:Start East. First left deflection places the river curving left; as it proceeds through a semicircle, its heading rotates left by a total of 180°.If the river enters the semicircle oriented roughly North after the first left, exiting 180° later gives a Southward orientation.From that Southward orientation, one more left (90°) brings the heading to East.Therefore, the final flow is East.

Verification / Alternative check:Think of a car: from East, a left arc of 180° flips your heading; an extra left 90° then realigns to East. Diagramming the arc confirms the end direction.

Why Other Options Are Wrong:West/North/South each correspond to intermediate states during the motion but not the final direction after the last 90° left.

Common Pitfalls:Interpreting the semicircle as “half-circle path in space” without tracking heading, or forgetting the final discrete 90° left.

Final Answer:East