Area of triangle base 10 height 5.

**The reasoning** The formula for the area of a triangle is: **Area = ½ × base × height** Given: base = 10, height = 5 Area = ½ × 10 × 5 Area = ½ × 50 Area = **25** This formula works for ANY triangle. The "½" exists because a triangle is literally half of a rectangle with the same base and height. Picture cutting a rectangle diagonally — you get two equal triangles! **Why the wrong options tempt you** - **A) 15** — You might have added base + height (10 + 5). That's not how area works! - **C) 50** — This is base × height WITHOUT the ½. You forgot that triangles are half rectangles, not full ones. - **D) 75** — Perhaps confused multiplication or added all three numbers somehow. **Quick takeaway** Triangle area is ALWAYS "half base times height" — remember: triangles are half of rectangles, so don't forget that crucial ½!