Calculate the size of angle x.
Give your answer to 1 decimal place.
8 cm
11 cm
15 cm

Answer:
45.6° (1 d.p)
Step-by-step explanation:
Using the cosine rule;
c = √( a² + b² - 2ab Cosx)
11 =√(8² + 15² - 2 (8) (15) Cosx)
11² = 8² + 15² - 240 Cosx
11² - 8² - 15² = - 240 Cosx
-168 = -240 cosx
cosx = 0.7
x = cos⁻¹ (0.7) = 45.57 ≈ 45.6°