Examples
Example 2
Example 3 Important
Example 4 Important
Example 5
Example 6 Important
Example 7 Important
Example 8 Important
Example 9
Example 10 Important
Example, 11
Example 12 Important
Example 13 Important
Example 14 (i)
Example 14 (ii) Important
Example 15
Example 16 Important
Example 17 You are here
Example 18 Important
Example, 19 Important
Examples
Last updated at Dec. 8, 2016 by Teachoo
Example 17 The focus of a parabolic mirror as shown in Fig 11.33 is at a distance of 5 cm from its vertex. If the mirror is 45 cm deep, find the distance AB (Fig 11.33). Since axis of parabola is in positive x-axis, Equation of parabola is y2 = 4ax Here, a = Distance of focus from vertex = 5 cm Now, Mirror is 45 cm Deep Hence, x-coordinate of point A = 45 x = 45 Putting x = 45 and a = 5 in (1) y2 = 4ax y2 = 4 × 5 ×45 y2 = 900 y = ± 900 y = ± 𝟑𝟎 Hence, Point C is (0, 30) & Point D is (0, 30) Hence OC = 30 cm & OD = 30 cm Distance CD = OC + OD = 30 + 30 = 60 cm So, AB = CD = 60 cm