Задача 50810 ПОМОГИТЕ РЕШИТЬ СРОЧНО ...

vk306899767

2020-05-19 14:06:56

ПОМОГИТЕ РЕШИТЬ СРОЧНО

sova

2020-05-19 14:26:31

★

|vector{c}|^2=vector{c}*vector{c}

|vector{a}+vector{b}|^2=(vector{a}+vector{b})(vector{a}+vector{b})=

=vector{a}*vector{a}+vector{a}*vector{b}+vector{b}*vector{a}+vector{b}*vector{b}=|vector{a}|^2+2*vector{a}*vector{b}+|vector{b}|^2



24^2=13^2+ 2* vector{a}*vector{b}+19^2 ⇒

2* vector{a}*vector{b}=[blue]24^2-13^2-19^2[/blue]

|vector{a}-vector{b}|^2=(vector{a}-vector{b})(vector{a}-vector{b})=


=|vector{a}|^2-2*vector{a}*vector{b}+|vector{b}|^2=


=13^2[blue]-24^2+13^2+19^2[/blue]+ 19^2=[b]2*13^2+2*19^2-24^2[/b]