More WJEC C3 Questions Added

New pages created containing questions from WJEC Core 3, 2005-2015:

Also, more questions (WJEC Core 3, 2005-2015) added to the Trigonometry page.

WJEC C4 2005-2015 added

All WJEC C4 questions from 2005-2015 have now been added. They are grouped by topic and can all be found under the Pure Maths drop-down menu.

Proof page added

Questions from WJEC module C4 on the topic of Proof by Contradiction added.