BACCALAURÉAT GÉNÉRAL ET TECHNOLOGIQUE SESSION 2009 ÉPREUVE SPÉCIFIQUE MENTION « SECTION EUROPÉENNE OU DE LANGUE ORIENTALE »
Académies de Paris-Créteil-Versailles
Binôme : Anglais / Mathématiques Sujet n° 11 Thème : ROTATION The first part of this page is a summary that can help you to do the exercise.
Z
X
Y
X’
O Y’
Z’
The letter L has been rotated through 90° clockwise about the centre O. The angle, direction and centre are needed to fully describe a rotation. We say that the object maps onto the image. Here, X maps onto X’, Y maps onto Y’ and Z maps onto Z’. The centre of the rotation is at the intersection of the perpendicular bisectors of XX’, YY’ and ZZ’.
EXERCISE: All lengths will be given correct to 3 significant figures.
In triangle ABC, BAC = 90°, BCA = 55° and AC = 20 cm. The triangle initially stood with AC on a horizontal surface. It was then rotated about the point C onto triangle A’B’C, where ACB’ is a straight line. (a) Calculate (i) the length of BC, (ii) the distance AB’, (iii) the height of A’ above CB’. (b) Describe fully the path which the point A followed under this rotation. (c) Calculate the length of the path which the point A followed under this rotation.
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