prove we can find two vectors in $V_1, V_2$ with zero inner product

Question

I want to prove that given $(\cdot,\cdot)$ an inner product space on $V$ above $F$ with $\mathscr{dim}=n$, if $n>2$ and $V_1,V_2$ are different linear subspaces of $V$ with $\mathscr{dim}= n-1$ then there are exist $v_1\in V_1$ and $v_2\in V_2$, while $v_1,v_2\neq0$, such as $(v_1,v_2)=0$. Would appreciate some help how to prove it.