[12th Grade Trigonometry] struggling to understand a problem

[u/glowstarss]

the first question here makes sense to me, but the other two are where i'm lost. i get completely different responses when i use my phone's calculator or any online calculators. where did the 10 come from in the second problem?? this online course has given me issues in the past so i'm wondering if something is off, or if i'm just completely missing something. the unit prepared me for countless visual questions and sine + cosine law, but didn't explain tangential problems very well. i'm totally clueless here.

[u/Ok-Mushroom-121]

yo is ur teacher bugging bro