Hi,
your post is actually quite important. For some reason, students do not score well on thr problems involving triangles (see the statistics of the past exams in the guide offered at
www.tmvscientific.com), and it is actually the topic where you can easily score if you learn several tricks.
1) For diagonal, use Pythagora's:
side a = 35 cm = 0.35 m, side b = 40 cm = 0.4 m.
a^2 + b^2 = c^2, hence diagonal is the square root of (0.35^2+0.45^2) = square root of 0.325
BE CAREFUL HERE!! Always note what is the required format of the answer at the exam! If you are asked for the exact value of the diagonal, leave it as the square root. Only calculate the value of the square root if
specifically asked, otherwise you may lose precious points. For example, if asked to provide the answer accurate to two significant decimal places, it is 0.57 m, or 57.01 cm. At three significant decimal places, 0.57 m, or 57.009 cm.
2) There is a trick here: you need two diagonals per window, hence you divide the total length of tape by two diagonals: square root of 50 divided by two square roots of 0.325, i.e. square root of (50/0.325) divided by two. Here you have to calculate the square root, and the result is 12.4 divided by two, which is 6.2. So, you can tape fully six windows!
3) If the problem brings more than 1 point, you have to show your workings at the exam.