Answer:
Question 3: 582 ft²
Question 4: 348 in²
Explanation:
Question 3:
Consider the solid shape given as being consisting of two rectangular prism. With careful examination, you'd observe that the offer one beneath has dimensions,
![l, w, h, as 15, 4, 9](https://img.qammunity.org/2021/formulas/mathematics/high-school/l6de62ujzrjzinvvzc5wm6aeskw6vo0b6m.png)
The second one has
![l, w, h, as 6, 4, 6](https://img.qammunity.org/2021/formulas/mathematics/high-school/rnmwasoxjcyv8z7gaocan9jmt2wenbooj7.png)
Surface area of the bigger rectangular prism = total surface area - area of the surface that is joined to the smaller rectangular prism.
Area of the face joined to the smaller rectangular prism = 4*6 = 24 ft²
Surface area of the bigger rectangular prism =
![2(wl + hl + hw) - 24](https://img.qammunity.org/2021/formulas/mathematics/high-school/wfrp3nkumo7weydf0yntih0kmv5aw7twng.png)
![2(4*15 + 9*15 + 9*4) - 24](https://img.qammunity.org/2021/formulas/mathematics/high-school/9j8h4ynesubxezizl7hjcuebow2u73wfxh.png)
![462 - 24](https://img.qammunity.org/2021/formulas/mathematics/high-school/7afw6onhb9zfhxzbeo7qg54czbn6zf6t7d.png)
Surface area of the bigger rectangular prism = 438 ft²
Surface area of the smaller rectangular prism = total surface area of rectangular prism - area of the surface that is joined to the bigger rectangular prism.
=
![2(wl + hl + hw) - 24](https://img.qammunity.org/2021/formulas/mathematics/high-school/wfrp3nkumo7weydf0yntih0kmv5aw7twng.png)
![= 2(4*6 + 6*6 + 6*4) - 24](https://img.qammunity.org/2021/formulas/mathematics/high-school/ppc4k88s3xbyyjambz47kn8go8sudfij1a.png)
![= 168 - 24 = 144 ft^2](https://img.qammunity.org/2021/formulas/mathematics/high-school/12c77078bksvi7niqis8nymdz4bzzf72ol.png)
Surface area of the solid = 438 + 144 = 582 ft²
Question 4:
Surface area of the triangular prism is given as: 2(B.A) + P*L
Where,
B.A = area of 1 triangular base = ½*height of the triangle*base of the traingle
B.A = ½*6*16 = 3*16 = 48 in²
P = perimeter of 1 triangular base = sum of all sides of the triangle.
P = 16+10+10 = 36 in
L = length or height of prism =
Plug in the values to find surface area of the prism
Surface area = 2(B.A) + P*L
= 2(48) + 36*7 = 96 + 252 = 348 in²
Surface area of prism = 348 in²