0
$\begingroup$

SO here is the picture. enter image description here

Vector AB=M'C-MA. This vector is perpendicular to the MA (tangent). I don 't understand why? I get why the angles MOM' and AMB are equal because they have their sides perpendicular, but why MAB is a right angle?

$\endgroup$
1
$\begingroup$

MAB is an isosceles triangle because its two sides MA and MB are the same length (unit vectors). Since it is an isosceles triangle, the angle MAB = the angle MBA. The sum of the angles in the triangle is $d\theta + 2 (MAB)=180\deg$. As $d \theta \rightarrow 0$ then $MAB \rightarrow 90\deg$.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.