1.45: Past-paper question 10

4PM1/1R/June/2025 — Question 10 · 15 marks

1.45 diagram 1
(a) Using a formula from page 2, show that
(i)sin2A=1cos2A2(i) \mathrm{sin}^2 A = \frac{1 - \mathrm{cos} 2A}{2}
(ii)cos2A=cos2A+12(ii) \mathrm{cos}^2 A = \frac{\mathrm{cos} 2A + 1}{2}
(5)
Figure 2 shows part of the curve C\displaystyle C with equation y=sinx\displaystyle y = \mathrm{sin} x and part of the curve D\displaystyle D with equation y=cos2x\displaystyle y = \mathrm{cos} 2x
Curve C\displaystyle C and curve D\displaystyle D intersect at the point A\displaystyle A
(b) Use algebra to find the exact coordinates of A\displaystyle A
(5)
The shaded region R\displaystyle R is rotated through 360\displaystyle 360^\circ about the x\displaystyle x-axis.
(c) Use algebraic integration to find the exact volume of the solid generated.
Give your answer in the form aabπ\displaystyle \frac{a\sqrt{a}}{b}\pi
where a\displaystyle a is a prime number and b\displaystyle b is an integer.
(5)