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If 2veca, 3vecb,2(veca xx vecb) are position vectors of the vectors A,B,C, of triangleABC and |veca|=|vecb|=1,vec(OA).vec(OB)=-3 (where O is the origin), then |
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Answer» TRIANGLE ABC is right-angled triangle `RARR 2.3costheta=-3` `rArr costheta=-1/2 rArr costheta=(2pi)/(3)` `=4|veca||vecb|^(2)sin^(2)theta+6veca.vecb=4.3/4-61/2=0` Angle C is `90^(@)`. |
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