A designer is creating a specialized acoustic panel. The panel ABCDA ABCDA\,ABCDA consists of a major sector ACBA ACBA\,ACBA of a circle with centre C C\,C and radius 10 cm, and a triangular region ACDACDACD, as shown in the geometry below. The point D D\,D lies on the radius CBCBCB. The radius of the circle is 10 cm, the length of AD AD\,AD is 9 cm and the angle ACD ACD\,ACD is 0.8 radians0.8\text{ radians}0.8 radians.

Find the area of the major sector ACBAACBAACBA, giving your answer to one decimal place.
Given that the angle ADC ADC\,ADC is obtuse,
find the size of angle ADCADCADC, giving your answer to 3 decimal places.
Hence find the perimeter of the panel ABCDAABCDAABCDA, giving your answer to one decimal place.
317 exam-style questions on OCR (MEI) A Level Maths 1.7 Trigonometry, covering 1.7.1 Solve right-angled triangles, 1.7.2 Definitions of sin, cos and tan for any angle, 1.7.3 Graphs of sin, cos and tan, 1.7.4 Exact values of trig functions (degrees), 1.7.5 Area of a triangle, 1.7.6 Sine and cosine rules, 1.7.7 Identity tan = sin/cos, 1.7.8 Identity sin^2 + cos^2 = 1, 1.7.9 Solve simple trigonometric equations, 1.7.10 Exact values of trig functions (radians) (A-level only), 1.7.11 Inverse trigonometric functions (A-level only), 1.7.12 Radians and degree conversion (A-level only), 1.7.13 Arc length and area of a sector (A-level only), 1.7.14 Small angle approximations (A-level only), 1.7.15 Sec, cosec and cot functions (A-level only), 1.7.16 Graphs of reciprocal trig functions (A-level only), 1.7.17 Pythagorean identities for sec and cosec (A-level only), 1.7.18 Compound angle formulae (A-level only), 1.7.19 Double angle identities (A-level only), 1.7.20 Expressions for a cos θ ± b sin θ (A-level only), 1.7.21 Use identities to solve equations (A-level only), 1.7.22 Proofs involving trigonometric functions (A-level only), 1.7.23 Trig to solve problems in context (A-level only), and 1.7 Trigonometry. Each one has a worked solution and a mark scheme showing where the marks go.