Higher November 2023 Paper 1 Q20
20 Here is triangle \(ABC\).
Find the size of angle \(ABC\).
You must show all your working. (4)
| Answer | Mark | Mark scheme |
|---|---|---|
| 120 | P1 | for using the cosine rule for any angle, eg \((5\sqrt{7})^2 = 10^2 + 5^2 - 2 \times 10 \times 5 \times \cos B\) |
| P1 | for a complete process to find \(\cos B\) eg \((\cos B =)\ \dfrac{10^2 + 5^2 - (5\sqrt{7})^2}{2 \times 10 \times 5}\) oe | |
| P1 | for \(\cos^{-1}\left(\dfrac{1}{2}\right) = 60\) or \(\cos B = -0.5\) | |
| A1 | cao |
Additional guidance
May be any angle; check diagram for working.
A correct answer with no supportive working gets 0 marks