Brain Out Level 16

Overview

A pentagram-style line drawing fills the upper part of the board, and the prompt asks how many triangles are in the figure. Below the drawing sits an answer counter at 0 with minus and plus arrows, plus Clear and OK buttons. The outer outline shows a few obvious large triangles, but the internal overlapping lines create smaller composite shapes as well, which is where most of the count hides. The accepted total is 11 triangles, combining the large outer shapes with the smaller ones formed at the intersections.

• Difficulty: Regular
• Estimated moves: 2

Step-by-Step Solution

1. Study the line drawing before touching the counter. Identify the outermost triangle first, then follow each internal segment to see where it crosses the others.
2. Count the large, easy-to-spot triangles that use the outer edges of the figure. These are the shapes most players find immediately, but they do not make up the full total.
3. Move inward to the smaller sections created where the lines cross. A triangle can be formed by two internal segments and one outer edge, or by segments that sit entirely inside the outline, so check each intersection region separately.
4. Keep a running tally as you confirm each closed three-sided shape. Avoid counting a quadrilateral or a trapezoid as a triangle, and do not double-count the same region through two different groupings.
5. When your tally reaches 11, use the plus arrow to set the counter to 11, clearing any wrong value first if one was entered.
6. Tap OK to submit the count. The board accepts 11 and the success panel appears. If the number is rejected, re-examine the inner intersections rather than changing the total to a random nearby value.

The puzzle is an overlap-count exercise. The extra triangles come from composite sections where internal lines meet, so the safest method is to start from the smallest visible shapes and work outward instead of counting only the big ones.

Strategy & Reasoning

Geometry puzzles like this punish a quick glance. The outer triangles are large and obvious, which makes a first count feel complete, but the crossing diagonals subdivide the figure into additional three-sided regions that are easy to miss. The accepted answer 11 reflects both the obvious outer triangles and the smaller composite ones hidden in the intersections.

Entering a small number fails because it counts only the large shapes. Entering a larger guess fails if it treats four-sided sections as triangles or counts the same region twice. The intended approach is systematic: trace each closed three-sided area once, mark it mentally, and add it to the tally. This is the same method used for other shape-counting boards in the game, where internal overlaps always contribute extra figures beyond the outer frame.

Tips & Common Mistakes

• Do not count only the big outer triangles. The accepted total includes smaller shapes formed where the internal lines cross, so stopping at the obvious ones undercounts.
• Do not force four-sided regions to count as triangles. Check that each shape you tally has exactly three straight sides before adding it to the total.
• If your submitted number is rejected, re-scan the inner intersections rather than guessing up or down. The accepted count for this pentagram figure is 11.