ABC is a right-angled triangle - Edexcel - GCSE Maths - Question 9 - 2018 - Paper 3

To find angle ABC, we will use the cosine rule.

The cosine of angle ABC is given by:

$$ext{cos(ABC)} = \frac{BC}{AC}$$

Here, BC is 7 cm and AC (the hypotenuse) is 11 cm:

$$ext{cos(ABC)} = \frac{7}{11}$$

Calculating this value:

$$ext{cos(ABC)} \approx 0.6364$$

Using the inverse cosine function:

$$ABC = \cos^{-1}(0.6364) \approx 50.3°$$

Therefore, the size of angle ABC is approximately 50.3°, rounded to 1 decimal place is 50.3°.