BECE Mathematics 2021 Paper

Concept:Angles are named by size:acute: less than $90^\circ$right: exactly $90^\circ$obtuse: between $90^\circ$ and $180^\circ$straight: exactly $180^\circ$Given:$x = 8$, angle $= (9x + 8)^\circ$Solution:Substitute $x = 8$: $9x + 8 = 9 \times 8 + 8$Multiply first: $9 \times 8 = 72$Then add: $72 + 8 = 80$, so the angle is $80^\circ$.Since $0^\circ < 80^\circ < 90^\circ$, the angle is acute.Key point: $80^\circ$ is close to $90^\circ$ but still less than it, so it is not a right angle.Answer:Option C (Acute angle)