NCERT Solutions for Class 9 Maths Chapter 7 Triangles Exercise 7.2 Solutions

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CBSE X Related Questions

1.

Prove the following identities, where the angles involved are acute angles for which the expressions are defined:\(\frac{(\text{1 + tan² A})}{(\text{1 + cot² A})} = (\frac{\text{1 - tan A }}{\text{ 1 - cot A}})^²= \text{tan² A}\)

      2.
      An umbrella has 8 ribs which are equally spaced (see Fig. 11.10). Assuming umbrella to be a flat circle of radius 45 cm, find the area between the two consecutive ribs of the umbrella.
      An umbrella has 8 ribs which are equally spaced

          3.

          The lengths of 40 leaves of a plant are measured correct to the nearest millimetre, and the data obtained is represented in the following table :

          Length (in mm)

          Number of leaves

          118 - 126

          3

          127 - 135 

          5

          136 - 144

          9

          145 - 153

          12

          154 - 162

          5

          163 - 171

          4

          172 - 180

          2

          Find the median length of the leaves. 
          (Hint : The data needs to be converted to continuous classes for finding the median, since the formula assumes continuous classes. The classes then change to 117.5 - 126.5, 126.5 - 135.5, . . ., 171.5 - 180.5.)

              4.
              A 1.5 m tall boy is standing at some distance from a 30 m tall building. The angle of elevation from his eyes to the top of the building increases from 30° to 60° as he walks towards the building. Find the distance he walked towards the building.

                  5.
                  Check whether \(6n\) can end with the digit \(0\) for any natural number \(n\).

                      6.

                      The following frequency distribution gives the monthly consumption of electricity of 68 consumers of a locality. Find the median, mean and mode of the data and compare them

                      Monthly consumption 
                      (in units)

                       Number of consumers

                      65 - 85 

                      4

                      85 - 105

                      5

                      105 - 125

                      13

                      125 - 145

                      20

                      145 - 165

                      14

                      165 - 185

                      8

                      185 - 205

                      4

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