AYUDAAA CON ESTO PORFAVOR?

Lo haré por otro método y veremos

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<img src="https://tex.z-dn.net/?f=%5Ctext%7BNos%20piden%20hallar%3A%7D%5C%5C%20%5C%5C%0A%5Ctext%7BMagnitud%20%7D%5Cleft%7C%5Cvec%7BR%7D%5Cright%7C%3D%5Csqrt%7B%5Cleft%28-%5Cdfrac%7B35%5Csqrt%7B3%7D%7D%7B2%7D%5Cright%29%5E2%2B%5Cleft%28%5Cdfrac%7B75%7D%7B2%7D%5Cright%29%5E2%7D%3D%5Cdfrac%7B5%7D%7B2%7D%5Csqrt%7B%28-7%5Csqrt%7B3%7D%29%5E2%2B15%5E2%7D%5C%5C%20%5C%5C%20%5C%5C%0A%5Cleft%7C%5Cvec%7BR%7D%5Cright%7C%3D%5Cdfrac%7B5%7D%7B2%7D%5Csqrt%7B147%2B225%7D%3D%5Cdfrac%7B5%7D%7B2%7D%5Csqrt%7B372%7D%5Capprox%2048.218253805%5Ctext%7B%20Km%7D%5C%5C%20%5C%5C%20%5C%5C%0A%5Ctext%7Bdirecci%5C%27on%20%7D%5Ctheta%20%3D%5Carctan%5Cleft%28%5Cdfrac%7B-%5Cdfrac%7B75%7D%7B2%7D%7D%7B%5Cdfrac%7B35%5Csqrt%7B3%7D%7D%7B2%7D%7D%5Cright%29%3D%5Carctan%5Cleft%28-%5Cdfrac%7B15%7D%7B7%5Csqrt%7B3%7D%7D%5Cright%29%20%5Capprox%20128.948275565%5C%C2%B0%0A" />.