Work out the length QR. Give your answer correct to 3 significant figures.

Total marks: 5

The length of QR is 29.9 cm

Step-by-step explanation:

Let us revise the sine and cosine rules

In triangle ABC:

⇒ sine rule

(AC)² = (AB)² + (BC)² - 2(AB)(BC)cos(∠B) ⇒ cosine rule

Let us use these rules to solve the question

In Δ PQS

∵

∵ PS = 11.7 cm

∵ m∠P = 95°, m∠Q = 28°

→ Substitute them in the rule above

∴

→ By using cross multiplication

∴ QS × sin(28) = 11.7 × sin(95)

→ Divide both sides by sin(28) to find QS

∴ QS = 24.82680292 cm

Now let us use the cosine rule to find QR

In Δ QSR

∵ (QR)² = (QS)² + (RS)² - 2(QS)(RS)cos(∠QSR)

∵ RS = 10.2 cm

∵ m∠QSR = 110°

→ Substitute these values in the rule above

∴ (QR)² = (24.82680292)² + (10.2)² - 2(24.82680292)(10.2)cos(110)

∴ (QR)² = 893.631984

→ Take √  for both sides

∴ QR = 29.89367799

→ Round it to 3 significant figures

∴ QR = 29.9 cm

check above link.

graphically?   well, you graph them both, the solutions is where they both intersect each other, since there are two solutions, meaning they will meet twice, or namely the linear will run into the quadratic curve twice, and where they meet, those x,y coordinates are the solutions to the system.

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step-by-step explanation: