Two flagpoles are 30 metres apart. One has height 10 m and the other has height 15 m. Two tight ropes connect the top of each pole to the foot of the other.

How high do the two ropes intersect above the ground?

How many different methods can you find to solve this problem?

What if the poles were a different distance apart?

Notes for Teachers – Flagpoles

### 2 Responses to Flagpoles

1. Khonyie Khonyane says:

it was interesting to my learners this one,i gave them as a group discussion,instructed to use graphical method and to choose their own scale,learners who are doing graphic drawing and physical science it was easy for them to understand when talking about scale,those who are not struggle a little bit till they understand,so even if different groups have chosen different scale,the height was the same when reporting.Two methods were used to solve this problem,graphical and algebraical,using trig functions.

2. Tsepo Tamako says:

I gave the problem to learners, most of them managed to draw the diagram. Learners were not able to calculate the height. I had to guide them. 1) they had to first calculate angles which the 2 ropes make with horizontal line. 2) workout the 3rd angle at the point of intersection of the 2 ropes,3) then workout any of the length from the bottom of one pole to the point of intersection using the sine rule 4) then could apply the sine of any of the 2 base angles and they obtained 6m