The diagram shows a rectangular gift box ABCDEFGHABCDEFGHABCDEFGH.
AE=6 cmAE = 6 \text{ cm}AE=6 cm
AD=5 cmAD = 5 \text{ cm}AD=5 cm
DC=12 cmDC = 12 \text{ cm}DC=12 cm

Calculate the size of angle ECAECAECA.
Give your answer correct to 3 significant figures.
Practise OCR GCSE Maths 3d Pythagoras and Trigonometry with exam-style questions for Foundation and Higher tier. 28 questions, matched to the OCR GCSE Maths (J560) specification and written in the written papers style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.