Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 5 - No. 5)
If a triangle has sides of length 3, 4, and 5, what is the cosine of the largest angle?
0
0.6
0.8
1
Explication
It's a right triangle. The largest angle is 90 degrees and its cosine is 0.