20/06/2025
Answer to the problem below:
Method 1: Conventional way (for students studying coordinate geometry):
Step 1: Find the red line equation: y = 2x + 2
Step 2: Find the blue line gradient: m = -1/2
Step 3: Find the blue line equation: y = -x/2 + 2
Step 4: Find the blue line x-intercept: (4,0)
Method 2: Quicker way (to apply when only the result is required, no additional questions about line equations):
2 right-angle triangles on either side of the y-axis are similar. Therefore, the ratio between the short and long side angle side are the same (1:2)
Thus, the length of the long right-angle side on the right is 2x2 = 4. The coordinate is (4,0)
In an exam, how do you know when to go for method 1, and when you can opt for method 2? 😉
