If |a| = |b| = 1 and |a + b| = √3, then the value of (3a – 4b).(2a + 5b) is
A. -21
B. \(-\frac{21}{2}\)
C. 21
D. \(\frac{21}{2}\)
Answer:B
If |a| = |b| = 1 and |a + b| = √3, then the value of (3a – 4b).(2a + 5b) is
A. -21 B. \(-\frac{21}{2}\) C. 21 D. \(\frac{21}{2}\)