trigonometry

He said after realising he had seen an exam question, instead of alerting the exam board, he deleted the image containing the trigonometry question.

“You were never going to teach a first grader a trigonometry lesson, right?” she said.

When students fell behind in areas like algebra, gaps could go unnoticed for a year or more as they moved to subjects such as geometry or trigonometry.

"I have lost count of the number of people who say they wish they had learnt about mortgages rather than trigonometry," she said.

Two high school students have proved the Pythagorean theorem in a way that one early 20th-century mathematician thought was impossible: using trigonometry.