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# Maths Questions For DSSSB Exams Q6. The area of two similar triangles ABC and DEF are 20 cm^2 and 45 cm^2 respectively. If AB = 5 cm, then DE is equal to
(a) 6.5 cm
(b) 7.5 cm
(c) 8.5 cm
(d) 5.5 cm

Q7. C1and C2 are two concentric circles with centre at O. Their radii are 12 cm and 3 cm, respectively. B and C are the point of contact tangents drawn to C2 from a point A lying on the circle C1. Then, the area of the quadrilateral ABOC is
(a) (9√15)/2 sq. cm
(b) 12√15 sq. cm
(c) 9√15 sq. cm
(d) 6√15 sq. cm

Solutions

S8. Ans.(b)
Sol. ∠ABC = (180° – 125°) = 55°, ∠ACB = (180° – 130°) = 50°
Let ∠BAC = x°
Now, ∠ABC + ∠ACB + ∠BAC = 180°
⇒ 55° + 50° + x = 180° ⇒ x = (180 – 105) = 75°
∴ ∠A = 75°

S9. Ans.(a)
Sol. In ∆ABC, ∠BAC + ∠ABC + ∠ACB = 180°
∴ 30° + 50° + ∠ACB = 180° ∴ ∠ACB = 100°
∴ ∠ECD = (180° – 100°) = 80°
∠AED=∠ECD+∠EDC = (80°+40°)=120°
∴ ∠AED = x° = 120°

S10. Ans.(b)
Sol. In ∆ABC, 40° + 90° + ∠B = 180° ∴ ∠B = 50°
In ∆EBD, ∠B + ∠BED + ∠BDE = 180°
∴ 50° + 100° + x° = 180° ⇒  x = 30°