d) 10 cm, 15 cm, 20 cm to the top of a building 3 m high the foot of the wall is 4 m.

Step 1: Tambua kuwa pembetatu hii ni pembetatu ya pembe mraba (right-angled triangle) kwa sababu ina alama ya pembe mraba. Ili kupata urefu wa upande $k$, tutatumia Theorem ya Pythagoras. Theorem ya Pythagoras inasema: $a^2 + b^2 = c^2$, ambapo $a$ na $b$ ni urefu wa pande fupi, na $c$ ni urefu wa hypotenuse (upande mrefu zaidi).

Step 2: Badilisha thamani zilizopewa kwenye fomula. Tuna upande mmoja mfupi $a = 15$ cm, upande mwingine mfupi $b = 8$ cm, na hypotenuse $c = k$. $15^2 + 8^2 = k^2$

Step 3: Kokotoa miraba ya namba. $225 + 64 = k^2$

Step 4: Jumlisha namba hizo. $289 = k^2$

Step 5: Tafuta mzizi wa mraba wa pande zote mbili ili kupata $k$. $\sqrt{289} = \sqrt{k^2}$ $17 = k$

Step 6: Andika jibu la mwisho na vitengo vyake. $k = 17 \text{ cm}$

Jibu la mwisho ni: $\boxed{17 cm}$

3 done, 2 left today. You're making progress.