Can you explain this experts

Dear Student,

W e k n o w, I f t w o v e c t o r s A a n d B a r e i n c l i n e d a t a n a n g l e θ, m a g n i t u d e o f t h e i r r e s u l \tan t i s, \sqrt{A^{2} + B^{2} + 2 A B \cos θ} P u t t i n g v a l u e s, \sqrt{5^{2} + 7^{2} + 2 \times 5 \times 7 \cos 60} = \sqrt{25 + 49 + 35} [\cos 60 = \frac{1}{2}] = \sqrt{109} N

Regards,