Question

A triangular shaped glass with vertices at A(– 5, – 4), B(1, 6) and C(7, – 4) has to be painted. If one bucket of paint covers 6 square feet, how many buckets of paint will be required to paint the whole glass, if only one coat of paint is applied

Answer 1

Given the vertices of the triangular glass is A (– 5, – 4), B (1, 6), and C (7, – 4)

Area of triangle ACB = `1/2[(x_1y_2 + x_2y_3 + x_3y_1) - (x_2y_1 + x_3y_2 + x_1y_3)]`

= `1/2[(20 + 42 - 4) - (-28 - 4 - 30)]`

= `1/2[58 - (- 62)]`

= `1/2 [58 + 62]`

= `1/2 xx 120`

= 60 sq. feet

Number of cans to paint 6 square feet = 1

∴ Number of cans = `60/6` = 10

⇒ Number of cans = 10