A GCSE maths question that has left many students scratching their heads can be solved easily with a simple formula, a tutor has revealed. Saadat, who teaches GCSE maths, English, and science, shared the problem on TikTok, noting that many pupils lose 'easy marks' by forgetting the formula.
The question involves an irregular pentagram with five interior angles. Given that Angle A equals Angle C, Angle B is 155 degrees, Angle D is three times Angle C, and Angle E is two times Angle C, students must find the value of Angle A. Without the right formula, the problem appears daunting.
The key formula is that the sum of interior angles of any polygon is (n-2) x 180, where n is the number of sides. For a pentagon (n=5), the sum is (5-2) x 180 = 540 degrees. Using this, the equation becomes: A + A + 3A + 2A + 155 = 540, which simplifies to 7A + 155 = 540.
Subtracting 155 from both sides gives 7A = 385. Dividing by 7 yields A = 55 degrees. Saadat advises students to memorise the formula to secure easy marks in exams. The tip has been widely shared on social media ahead of the GCSE exam season.
