5 thoughts on “PnC in Geometry – 3-D painting 2

  1. sir…..prism main 3 side Jo rectanguler shape main hai …vo to aapas main identical Hongi…so for first colour let red there are two possible sides can be chosen..please explain this

    • I have started by choosing a side and not a colour. I chose to colour the top/bottom first and then the rectangular sides. You can start by choosing a colour as well, that way you will have two cases, you will need to calculate both and add. The answer should come to the same though!


  2. Sir, though not related to topic, need another way to quickly solve this question. Consider a circle with r = 5cm. PQ is a diameter of circle while QR (R is an external point) is a tangent to circle touching the circle at Q. PR intersects the circle at point T. TS is the tangent to circle touching at T. TS is meeting QR at S. If PT is 8 cm, what is the length of RS?

    • Sir, the way was use of tangent secant theorem for finding the QR by considering RT as a variable. Then proving triangle POT, QTS and TSR as isosceles triangle and claiming RS = 1/2 * QR. But I was trying for any quicker way. Similarity I tried but dint get the reqd result.

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