Which of the following are right-angled triangles?

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 $y$, 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 $a = 10$ cm, upande mwingine mfupi $b = y$, na hypotenuse $c = 26$ cm. $10^2 + y^2 = 26^2$

Step 3: Kokotoa miraba ya namba. $100 + y^2 = 676$

Step 4: Toa 100 kutoka pande zote mbili za mlinganyo ili kutenga $y^2$. $y^2 = 676 - 100$ $y^2 = 576$

Step 5: Tafuta mzizi wa mraba wa pande zote mbili ili kupata $y$. $\sqrt{y^2} = \sqrt{576}$ $y = 24$

Step 6: Andika jibu la mwisho na vitengo vyake. $y = 24 \text{ cm}$

Jibu la mwisho ni: $\boxed{24 cm}$

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