Задача 30244 ...

dashokkkk

2018-10-15 21:30:43

Решить с объяснением!
Пожалуйста ♥️

sova

2018-10-15 22:08:08

★

[vector{a},vector{b}]=|vector{a}|*|vector{b}|*sin ∠ (vector{a},vector{b})
причем
[vector{a},vector{a}]=|vector{a}|*|vector{a}|*sin 0=0


[vector{a_(1)}+vector{a_(2)},2*vector{a_(1)}+vector{a_(2)}]=

=[(vector{a_(1)},2*vector{a_(1)}]+[(vector{a_(2)},2*vector{a_(1)}]+
+[vector{a_(1)},vector{a_(2)}]+[vector{a_(2)},vector{a_(2)}]=

=2*0+2*|vector{a_(1)}|*|vector{a_(2)}|*sin( π/6)+ +|vector{a_(1)}|*|vector{a_(2)}|*sin( π/6)+0=

=18

|[vector{a_(1)}+vector{a_(2)},2*vector{a_(1)}+vector{a_(2)}]|=18