19(b) (= 27 18) M1 Invisible brackets must be recovered for M1 (3√3)2 – (3√2)2 – Alt 1 or 3 A1 √9 M1Dep Dep on M1, not on A1 as well Area ABD = 0.5 3 and their  3√2 area ADC = 0.5 their 3 √2   M1Dep Sum of two correct areas for their AD Area ABD = 0.5 3 + 3√2 their  area ADC = 0.5 their 3 √2   A1 6√2 19(b) (= 27 18) M1 Invisible brackets must be recovered for M1 (3√3)2 – (3√2)2 – Alt 2 or 3 A1 √9 + (= M1Dep Dep on M1, not on A1 as well 3√2 √2 4√2) M1Dep Sin ABD = their 3 and Area = ÷ 3√3 1 0.5 √2 √ A1 6√2
19(b) Alt 1 (3√3)2 – (3√2)2 (= 27 – 18) M1 Invisible brackets must be recovered for M1 √9 or 3 A1 Area ABD = 0.5 their 3  3√2 and area ADC = 0.5  their 3  √2 M1Dep Dep on M1, not on A1 as well Area ABD = 0.5 their 3  3√2 + area ADC = 0.5  their 3  √2 M1Dep Sum of two correct areas for their AD 6√2 A1 19(b) Alt 2 (3√3)2 – (3√2)2 (= 27 – 18) M1 Invisible brackets must be recovered for M1 √9 or 3 A1 3√2 + √2 (= 4√2) M1Dep Dep on M1, not on A1 as well Sin ABD = their 3 ÷ 3√3 and Area = 1 0.5 √ √2 M1Dep 6√2 A1