To determine the measure of IG given that TU = 12, we need more context on the relationship between IG and TU. It appears that there might be specific geometric relationships or proportionality that are not provided in your question.
If IG is part of a geometric configuration involving TU, such as lines, segments, ratios, or a proportion of lengths, please provide that additional information so I can help you calculate IG precisely.
For example, if there was a ratio or a segment division stated, we could apply that to find the length of IG. Without further context, I cannot definitively determine IG.
Please provide more information regarding the relationship between IG and TU, and I will be happy to help!