Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 5 - No. 4)
If you have a triangle with sides 6cm, 8cm and angle between the two is 60 degrees, what is the length of the third side?
7.84cm
4.0cm
7.21cm
9.24cm
Giải thích
Using the cosine rule, c² = 6² + 8² - 2 * 6 * 8 * cos(60), c = 7.211