If T and R are the tread and rise of a stair which carries a load w per square metre on slope, the corresponding load per square metre of the horizontal area, is
A
$$\frac{{{\text{w}}\left( {{\text{R}} + {\text{T}}} \right)}}{{\text{T}}}$$
B
$$\frac{{{\text{w}}\sqrt {{{\text{R}}^2} + {{\text{T}}^2}} }}{{\text{T}}}$$
C
$$\frac{{{\text{w}}\sqrt {{\text{R}} + {\text{T}}} }}{{\text{T}}}$$
D
$${\text{w}}\frac{{\text{R}}}{{\text{T}}}$$
Correct Answer: $$\frac{{{\text{w}}\sqrt {{{\text{R}}^2} + {{\text{T}}^2}} }}{{\text{T}}}$$
