Question

Two Vectors have magnitude 6unit and 8unit.
Find
the magnitude of their resultant if angle between
them is
(i) o (ii)180' (iii)60° (iV) 120 (v )90°​

Answer 1

$using \: \: parraleogram \: law \: ofvectr \: addition$

$r = \sqrt{x {}^{2} + y {}^{2} + 2xy \cos( \alpha ) }$

• $r = \sqrt{6 {}^{2} + 8 {}^{2} + 2(6)(8) \cos(0) }$

$= \sqrt{ 36 + 64 + 48 \times 2}$

$= \sqrt{100 + 96} = \sqrt{196}$

• $r = \sqrt{6 {}^{2} + 8 {}^{2} + 2(6)(8) \cos( \alpha ) }$

$r = \sqrt{100 + 0}$

r=10

• $r = \sqrt{100 + 96\cos( \alpha ) }$
• $r = \sqrt{148} = 12( \approx)$
• $r = \sqrt{100 + 96 \cos( \alpha ) }$
• $r = \sqrt{100 + 48 \sqrt{3} }$
• $r = \sqrt{100 + 96 \cos( \alpha ) }$
• $r = \sqrt{100 + 0} = \sqrt{100} = 10$

leaving some calculations for you