A rafter makes an angle of 22.5° with the roof joist, as shown How tall is the board supporting the middle of the roof?

≈ 5 ft

Step-by-step explanation:

Using the tangent ratio in the right triangle.

let the height of the board be h , then

tan22.5° = = ( multiply both sides by 12 )

12 × tan22.5° = h , then

h ≈ 5 ft ( to the nearest whole number )

v v cj van config k tbs eng r.c r.c fcb fb gb frfr

225x²+4=0

225x²=0-4

225x²=-4

x²=-4/225

x=±√-4/225