Truth as such is fixed fact about an event in reality but that is for a posterori truth that is sentient but apriori truth exists without the necessity of any occurring event. The mathematical proofs fall into the latter. It could not be known outwardly as a rote and something must make the axioms or theorems inwardly. Unlike historical truths that are more contingent having no necessity as compared to the laws of nature which are non-arbitrary and demands necessity as the required condition. Mathematical truths though like laws of nature are not contingent and must demand the essentiality of proof.
A philosophical cognition is based upon both existence and essence while mathematical truths are concerned usually with existence. In mathematical truths, insight is external to the substance and as a result, the truth is altered by it. So when I say the sum of two right angles is 180 degrees, the insight into the idea of right angles is external to the proof of it being 180 degrees and thus the proof is altered by it.