$$$C$$$ lies on a circle with diameter $$$A D$$$. $$$B$$$ lies on $$$A C$$$ and $$$E$$$ lies on $$$A D$$$ such that $$$B E$$$ is parallel to $$$C D$$$. $$$A B=21 \mathrm{~cm}, C D=18 \mathrm{~cm}$$$ and $$$B E=13.5 \mathrm{~cm}$$$. Work out the radius of the circle. $$$...............\mathrm{cm}$$$

Mathematics

IGCSE&ALevel

CAIE

Exam No：0580_s20_qp_21 Year：2020 Question No：13

Answer:

$16.6$ or $16.64 \ldots$

Knowledge points:

E4.5 Use the basic congruence criteria for triangles (SSS, ASA, SAS, RHS).

E6.2.1 Apply Pythagoras’ theorem and the sine, cosine and tangent ratios for acute angles to the calculation of a side or of an angle of a right- angled triangle. (Angles will be quoted in degrees. Answers should be written in degrees and decimals to one decimal place.)

E6.2.2 Solve trigonometric problems in two dimensions involving angles of elevation and depression.

E6.2.3 Know that the perpendicular distance from a point to a line is the shortest distance to the line.

Answer:

Knowledge points:

Solution:

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