The altitude of an isosceles triangle splits the base into two congruent segments, so $BD = DC = 7$.  Applying the Pythagorean Theorem to $\triangle ABD$, or remembering the 7-24-25 Pythagorean triple, gives $AD = 24$, so the area of $\triangle ABC$ is $(24)(14)/2 = 168$.
In any isosceles triangle $ABC$ with $AB=AC$, the altitude $AD$ bisects the base $BC$ so that $BD=DC$.

Determine the area of $\triangle ABC$.

[asy]
draw((0,0)--(14,0)--(7,24)--cycle,black+linewidth(1));
draw((7,24)--(7,0),black+linewidth(1)+dashed);
draw((7,0)--(7,1)--(6,1)--(6,0)--cycle,black+linewidth(1));
draw((5.5,-4)--(0,-4),black+linewidth(1));
draw((5.5,-4)--(0,-4),EndArrow);
draw((8.5,-4)--(14,-4),black+linewidth(1));
draw((8.5,-4)--(14,-4),EndArrow);
label("$A$",(7,24),N);
label("$B$",(0,0),SW);
label("$C$",(14,0),SE);
label("$D$",(7,0),S);
label("25",(0,0)--(7,24),NW);
label("25",(7,24)--(14,0),NE);
label("14",(7,-4));
[/asy]