- 18 The diagram shows triangle PQR.
Diagram NOT
accurately drawn
P
17.8 cm
360
R
26.3 cm
Calculate the length of PR.
Give your answer correct to 3 significant figures.

The length of PR is 15.8 cm

Step-by-step explanation:

We will solve the question using the cosine rule

In ΔPQR

∵ (PR)² = (PQ)² + (RQ)² - 2(PQ)(RQ)(cos∠Q)

∵ PQ = 17.8 cm

∵ RQ = 26.3 cm

∵ m∠Q = 36°

→ Substitute them in the rule above

∵ (PR)² = (17.8)² + (26.3)² - 2(17.8)(26.3)(cos36)

∴ (PR)² = 316.84 + 691.69 - 936.28(cos36)

∴ (PR)² = 251.0635685

→ Take √ for both sides

∴ PR = 15.8449856

→ Correct it to 3 significant figures

∴ PR = 15.8 cm

∴ The length of PR is 15.8 cm

∠lno ≅ ∠lnm

∠oln ≅ ∠mln

step-by-step explanation:

given   that triangle lno is congruent to triangle lnm.

we have to fill up the blanks in the given question.

according to above order of congruency   kept in mind we can say that

∠lno ≅ ∠lnm

∠oln ≅ ∠mln

ln ≅ ln due to common in both.

hence, by sas congruency,

the side angle side rule   states that if two sides and the included angle of one triangle are congruent to another triangle, then these two triangles are congruent.